I don't see your boyfriend as mature (or settled) enough to settle down and marry. If you really like him, not just the idea of him and having someone who you could marry, I would go back to being "a girlfriend" instead of prospective finance and see what develops during this next tour. I would also date others while he's away (but write, send him packages, etc.). That you all have been messing around this long seems a little iffy to me; it's my experience that exclusive love, both people want to be with the other all the time (and don't have time for flying alternate girlfriends to visit parents so they can "vote").

I agree with you that the mother and other girlfriend are too complicated to mess with, that that situation is not as you would want or deserve before marriage to this guy. I have a 33 year old stepson who has serious girlfriends for many years and we all get attached and hope they marry (the last one) but when they break up, it wouldn't occur to me or his mother to contact the old one after he brings around the new. We might talk amongst each other (other brothers, sister-in-law, father, etc.) as to which we prefer but we go with the flow, it's his life.