Is your loved one receiving any care or refusing to see a physician? What is the nature of the paranoia and how long has it been going on?
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From what you've described, it does seem that he has a lot on his plate. Personality disorders are not something that can be cured per se. A person can learn how to manage their symptoms to an extent if willing to. You've mentioned that he's not into receiving treatment. Most likely, the behaviors you're struggling with in regard to his behavior, would remain the same (unless he makes some changes).
If he has narcissistic traits, it may be what you're drawn to, perceiving him as knowledgeable or intellectual. Over time, you may tire of the tendency to be self centered though. In a healthy relationship, you'd want to have mutual power/control.
As far as how you deal with all of his issues, it would depend on your own coping skills and what and for how long you're willing to deal with.
Because of your feelings for him right now, you may try to persuade him to at least consider consulting with a professional because, even though he does not find a problem with the way he is behaving, you do. And, you're his partner now.
Something else to consider would be- what you hope to get out of the relationship and if he is truly capable versus unwilling to provide that long term.
With the paranoid tendencies, you may feel drained sooner or later having to defend yourself. To him, these suspicions are real. They do not however indicate true love. This does not mean he does not feel love; it rather means that his paranoia is driving him towards possessiveness and control over you.
You could try to separate the person from his symptoms. It would take a lot of you and it would be a process. You may have to make some sacrifices along the way. It is generally not suggested that you try to convince him that his paranoia is not real. Rather, speaking to him about how it affects you and the relationship as a whole may be more helpful. Giving him a choice is another option. You can pose a question to him of sorts like- what may be more doable for you- to speak to a professional (you can offer to go with him to the appointment) or to look for ways to work on the things (which you find troublesome/unhealthy for the relationship) through self introspection, self help/workbooks etc. Use some concrete examples that show how his actions had led to failed relationships, jobs, goals, etc.
There are some support groups set up by NAMI.org that assist loved ones in dealing with mental health issues of their partners. You can find one nearest you and see what it offers.