Yeshivishhock- it sounds like you have a real dilemma on your hands. I very much sympathize with you.
I can’t offer you much in the way of advice or personal experience since I have never experienced this and do not know what I would do, and I have no idea what the right thing to do is either. (well, actually I can guess what I would do – I would almost definitely marry him, but only because I would be acting on my emotions, and not necessarily because it would be the right thing to do)
I am sure that there are people who have acted one way and are happy they did so, and others who acted the other way and are happy that they did so.
The one suggestion I would make is to remember that as Jews, we have to remember that the purpose of all our actions is to serve Hashem. When making any decision, the decision must be based on one factor alone: Will this bring me closer to Hashem or c”v, the opposite?
When it comes to marriage, that is definitely the most important question. It is also crucial to think about the kind of home you want to build and the way in which you want to raise your children. If you marry him, will you be able to build the kind of home you want and raise your kids the way you want to? Since that is the purpose of marriage, these are important issues to think about.
Right now, you are infatuated with him, but from what I have heard (no personal experience), infatuation may not be enough of a basis for marriage. A marriage has to be based on common goals and values.
I am not saying that the answers to these questions is definitely no. It is possible that you do share the same basic values. But it is something to think about.
kol hakavod for having the strength to spend the last year and a half dating other guys when you were really interested in dating this guy! You obviously have a lot of internal strength, since that must have been a really hard thing to do. I wish much continued hatzlacha in making the right decision, whatever it may be.