We've Been Together for Years and Still No Proposal! When to Give Up on Him
Obviously you two have discussed the subject of marriage at times, yes? Consider how he responded to those conversations. A man who is commitment phobic will do whatever is necessary to shift the discussion to something else. He may try and get you to focus more on how great things are right now and he'll often say that you shouldn't worry so much about the future. That's because his fear or inability to commit is overwhelming him and he doesn't see any reason for the relationship to change. If he's happy being your long term boyfriend, he's not going to see any viable reason to change it.
Some men shy away from the idea of marriage because of extenuating circumstances. Things like not feeling financially comfortable, or struggling with the after effects of a very painful divorce within their own family are both reasons why some men just can't wrap their minds around the idea of a proposal. If your guy doesn't feel that he can support himself in the way he'd like, he's certainly not going to pop the question. The same is true if he watched his parents shift from loving one another to hating one another because of a bitter divorce. In fact, some men are so scared that history will repeat itself that they won't ask their girlfriend to be their wife because they're fearful of eventually losing her.
You love your guy so you definitely have some insight into what makes him tick. If he has confided in you that he's still deeply impacted by his own parents' marriage issues, consider that it may just take him longer to want to dive into a more committed situation. If he's the type of man who shuns any conversation that has to do with commitment, he may just not be marriage material.
Deciding to end a relationship because you don't see commitment on the horizon is painful but sometimes may be the necessary step to take. No one can decide what you should do but you. Just ask yourself whether you'd be content still being his girlfriend in a year, five years or ten years. If the answer is "no," and he's rigid on his decision not to marry, you have to seriously consider what is best for you.
You must also weigh how important the actual idea of marriage is. Many couples live long, happy and fulfilling lives as life partners. This arrangement lacks the engagement ring, ceremony and anniversaries. However, it does offer a life with the man you adore. Is it the idea of being married or is it the man you love that is most important to you? Only you can decide.