You seem to believe that SHE doesn't have the discipline or motivation to want to grow more mature and thus manage to be more of what you want from her. And I'd guess that you haven't considered what YOU would need to learn about coping with your own emotions as well as hers in order to make the relationship work; and you may not have considered how compatible you might be as a couple (in what you want in a partnership) even if you DID try to make it work. So I'll explain some of where I'm coming from, since I'm 74 and been an individual and couples therapist since 1973.
I had 3 relationships of around 3 years after my first of 9 years (not a legal marriage but a moral marriage in terms of full bore unreserved commitment), where compatibility seemed to be very high, because my GF didn't try to find out who she was and just followed me around. And in each of those 2nd 3rd & 4th cases, when the romantic energies moderated (after the first one) a clear-eyed assessment of the compatibility and emotional harmonies convinced me that the relationship would not satisfy me for a lifetime, so I broke up (#2, 4) or she did (#3).
So I'd advise you to evaluate your relationship with your first wife, and any other relationship of a year or longer, and this one of 3 years in the following ways: Use the 13 types of Intimacy I'm putting into this transcript to compare A. How much you WANT(ed) to have that intimacy with partner 1, 2(if there was one) & 3 (this one) and B. How well that intimacy type worked and was satisfying between the two of you. Here's the list:
Types of Intimacy [From Love & Intimate Relationships: Journeys of the Heart, Brown & Amatea, 2000.]
1. Physical. Familiarity & closeness with another’s body in work & play, medical care, touch, massage.
2. Sexual. Erotic pleasure sharing. (The typical default meaning of intimacy for men, whether verbal or emotional sharing are involved or not.)
3. Emotional. Empathic attunement & expressing emotions. (The typical meaning for women, though the reality may be that one is giving & receiving only the emotions one wants, and not Crisis (9) or Conflict (10).)
4. Intellectual. Sharing spheres of ideas.
5. Aesthetic. Sharing experiences of beauty and excellence.
6. Creative. Sharing acts of creation together, including brainstorming.
7. Recreation. Fun, sports, play.
8. Work. Cooperating in tasks or occupation, wage-earning.
9. Crisis. Facing crises, problems & pain together.
10. Conflict. Struggling with differences & frustrating interaction cycles.
11. Commitment. Trust & mutuality from common investment of self.
12. Spiritual. Sharing religious, spiritual & transpersonal experiences & concerns.
13. Communication. Verbal sharing and understanding. (Typically combined with Emotional, Intellectual, crisis, conflict, etc.)
I'd expect that you'd notice that not many of these types are highly functioning with your present girlfriend, such as perhaps that Emotional Intimacy isn't very achievable with her because her emotions are so overwhelming to her and your reactions are to just back away and not even try to feel and express your own to her. AND perhaps that you don't want or need to share that many of them with any of the women you've been involved with, even the one who was your wife. For example, when I look back on my first great love (20-29) I shared #1, 2, 4, 5, 7, 9, 11 (& 13 only partial); and my wife (from my age 41 to 73) who was a therapist like I am, it was #2, 3, 4, 9, 10, 11, 13--and I took care of her through her first 2 and final 2 out of 11 years of metastatic cancer.
The value of doing this self-evaluation can be that you begin to realize what you're currently really interested in having with a woman partner--since many single parents don't seek as much intimacy with a sexual partner because they're getting enough of some types of companionship with their children (esp true for women). And I've found that as I matured, NOT having emotional intimacy with my first great love was NOT acceptable to me when I was 40 (and living in one of my 3 year love partnerships)--because by then I was a therapist and couldn't be happy with someone who couldn't cope well enough with emotions to be open & vulnerable with them, AS MY NEW experienced therapist GIRLFRIEND IS NOW (where at 5 months together only #5, 9 & 10 are as yet not well enough developed to know whether we'll harmonize them satisfactorily or not).
You might also object to an implied standard of achieving more types of satisfying intimacy as a definition of "desirable relationship"--because like my therapist wife of 32 years you're an introvert (who didn't want to share her spiritual life or her reading-books-life much at all) or a "guys'club adventurer," nature-lover or computer-game-lover who doesn't want to spend too much time with his own wife. In Most non-Western societies men & women don't expect so much intimate time that their personalities hugely overlap, and then both partners get more chance to grow in separate directions and manage to keep the RIGHT KINDS of intimacy so they'll still be satisfied with each other for a lifetime. Or like me, you use each trial partnership to find out what is fulfilling and what is not, and refine your desires of what kinds of intimacy you want (and more or less couple intimacy, vs buddy-intimacy, vs group, and vs solitude (where learning #4, working #8, aesthetic appreciation #5 and spiritual activity #12 can be highly rewarding without a partner to share them with).
This is more than what you're asking for; but it's a context within which to consider your current choice of which side of the fence you want to get off on, reunion until it's snarled up again, or ending it, where you'll have to deal with unwanted loneliness and what-ifs.