I think you need to listen to your wise self. You have doubts because there is reason to have them. Throughout the history of your relationship, he has “borrowed” money or not paid his share. Why do you think it will be different now? That is not to say that all marriages need to be alike in terms of the division of financial responsibilities. But for a marriage to last, there has to be a clear agreement and reliable follow through by the people involved — and there has to be an understanding of how you will handle things when circumstances change. (Will he step up, for example, if you need to cut back your contribution in order to get more schooling or to take a different job? How will you divide responsibilities if you have a child?) You and your boyfriend don’t seem to be on the same page.
I worry that by not paying attention to your doubts you are setting yourself up for the divorce you fear. However much you love this man, you can’t count on him to do his financial part. That is going to get old real quick. You and your boyfriend need to come to an agreement he can stick to and you can live with.
That may mean taking a step back from living together. You both need to know that you are serious. If you can’t negotiate a real agreement on your own, it would be advisable to go to see a couples counselor for a few sessions to work it through. Please do this work before you get engaged. If you don’t it will likely become an issue that will erode your relationship.
I wish you well.