They finally broke up after years of dating. He soon met another and married her. Why? Because she gave him an ultimatum. People will take as much rope as you give them.....it's human nature.......
I do not agree. Ultimatums are BAD.
1) Humans are prideful creatures. Not always bad, but in this case it would be. No one likes being forced to go one way or another. (Like when you were young and about to wash dishes and your parents yelled "Go wash the dishes!")
2) Being "forced" to choose likely will put him against you, even if he really is into you, because of pride OR if it goes your way, he may resent you or the decision he made.
So, simply talk, like NC advised and find out whats going on. Then proceed to allow him to exercise his options as he please.