Your concerns are important, and there are more than just a few aspects to consider. Her age and yours, her legal status in your country (I can't see online where you are) and your cultural differences, and the commitments you have made with her up to the time she left for China, for starters. Three years is in fact a very normal time for a relationship crisis to develop, because the natural romantic chemistry of new love is likely to simmer down--because in the aeons before birth control any couple engaging in intercourse would have given birth to a baby, so the mother's emotional passions would naturally shift towards assuring the development of her infant and the man's passionate priorities would be more free to focus on assuring his family's social and financial security and success.
I'd like to reserve judgment until I hear more about your partner's sources of personal support and her career and financial goals in your country before I give more professional advice. But do you think she ha no hint that your relationship isn't satisfactory? [It is, however, also quite normal for couples to NOT develop the communication structures before the third year for bringing up aspects of their life that need change, because both people may be afraid of "rocking the boat" of the relationship and thus injecting difficult emotions & unpleasant days into what has been a low-conflict & high-pleasure life together. Yet the moderating of their romantic and sexual passion lowers their rewards for keeping silent, while the potential discomfort from unresolved problems looms larger.
So it makes sense to "throw in the towell" and assume that there's just too much that isn't working out, so one actually makes up his mind in advance, without trying to find out if anything can be done.
If your cultural differences are large, then I'd expect that you may believe that she is not able to deal with differences in "normal" expectations about how relationships are conducted and repaired in the ways that you view as possible & productive. So you may have already concluded that seeing a counselor or pastor or other intermediary would not help. But I need to wait until I've heard more about how you've arrived at your decision to break up. If you don't want to discuss that or consider possible approaches to repairing your relationship, then (until I learn what you want to tell me about my questions above) I would Guess that it MIGHT be better to communicate your concerns about the relationship and hesitations about continuing it while she is home with her family as a support system around her, so she can find people to discuss her reactions with. Or do you have reason to assume that her family might be unsupportive, because of possible culture-based attitudes about it being HER fault and failure if you're not satisfied with her as a love partner? Are you perhaps also concerned that her family might just insist that she drop her connection with you like a hot potato to withdraw from the shame of a failed partnership?
These are speculations since I don't know exactly what your own culture is and hence can't get enough background to make intelligent extrapolations about your differences in your relationship. If I knew YOUR culture and your expectations about love, and more about HER expectations about where she wants to live and work, then I could advise you more carefully. We have at least a week to discuss your concerns, so tell me a much as you want.
I've not done enough cross-cultural counseling with Chinese/Canadian or Chinese/American couples to be sure of what to expect from her family--and how they could be affecting her. Tho it's pretty impressive that she may prefer emigrating to Canada over returning to live close to family in China. I'm not sure if there is anyone else among the relationship experts who has more of that knowledge than I do. I know some aspects of Asian female relationship style. And my landlord where I live north of Atlanta, GA is Chinese (doesn't even speak English) and their son is bicultural--so I can interview him (and I've dealt with a variety of other cross-cultural couples.
If you can reasonably guess that she does NOT want to stay in China with her parents, then she'd be better off if you found a Chinese- of Japanese-American counselor in your part of the US to preside over the dissolution of your relationship. Because even if she's going to move back to Waterloo (who's there to make her feel safe?) she's probably going to need some Westernizing of her emotional habits for dealing with her grief & shame (That she "might hurt herself" means depression capped by shame, so you're absolutely RIGHT to realize that she may not have the behavioral coping strategies needed to cope with relationship loss.
I'm pretty skilled with the components of grief, which DOES include shame (that's SO large in many Asian societies, esp where personal psychological struggles are always kept secret. You may be guessing correctly that she wouldn't even want her closest family to know of any problems in her partnership with you--in that case she may [just got your latest communication about her PhD "failure"--do you think she could resume and finish a degree somewhere else IF she developed enough Westernized psychological self-supportive capabilities thru grief therapy with a woman she could identify with and trust?
It's actually possible that her habit of keeping so much about herself secret from everyone could lead directly (psychodynamically) to the paranoid characteristics you've observed: it could be a form of psychic Implosion resulting from her clash with the pseudo-extraversion of North American culture.
I'll mention now also another key aspect of an East-Asian female approach to coupling: That it's her job to "know" intuitively what you want and what pleases you, so she can keep you happy (food, sex & praise, the big 3 and deference)--yet when that doesn't work, her life doesn't add up, and failure is not an option. So shame roars in, and she'd be withdrawn, depressed, and/or angry at you as a result. This may be only approximately accurate--and you've already been showered with quite a bit of the nittygritty of family-nightmares.
It's 4:30am my EST, but I have to go put my cooked yoghurt into the refrigerator before going to bed. What do you think about my suggestion that you COULD keep the emigration potential open for her (if her visa situation is secure) by waiting until she returns and inviting her into couple counseling with an Asian-American woman (that you'd have to locate in person in your area--I've not seen an Asian-American name among other relationship experts here)? That way she wouldn't just collapse into her home environment because you've brought up relationship problems in writing and her family convinces her to stay with them.
Psychodynamics is a modern umbrella word for the psychoanalytic school (Freud, Jung etc) that observes the effects of mental&emotional forces in us that combine, accumulate and influence our experience & behavior without being controllable by our conscious thoughts & intentions, like underground rivers. And psychic Implosion is a metaphorical description of a cumulative effect from keeping emotional issues inside: such that her numerous paranoid ideas may actually be projections outward onto malevolent other people of her own overzealous efforts to keep her own anxiety & feelings inside so they can't be seen (and be held against her as unseemly & improper) by others. In a communal culture like the Chinese society, everyone would know everyone else's business unless everyone does their utmost to keep inner reactions from showing (must be "inscrutable"). so proper external behavior is a psychic strait-jacket that actually makes most people likely to suffer from inadequate self-expression (by Western standards), and also from Shame when any expression or action that "shouldn't be broadcast" or known gets known (like any "failure.") This is why I think that a bicultural Asian/NAmerican counselor would be able to help her learn how to bridge her culture-clash and possibly greatly reduce her paranoid thinking, which may be driven to exaggeration by being both culturally isolated and living with too much culturally defined "failure."
I'm willing to arrange a time to talk on the phone with you--via "Offer Additional Services"--or to offer up your question to anyone who knows Chinese culture better than I do. However, it sounds to me like her parents educational level is pretty unsophisticated, so it may just boil down to the question of whether she wants to give up her provincial roots for a Western success-style--which is a big loss, and a step toward world-citizenship if she chooses it. Yet you also seem to be saying you DON'T want to play a role in helping her make that transition without you, because you don't want to be her mate anymore. (Which brings us back to the world-wide biologically based 3 year relationship cycle.)