It doesn't sound like a fear of intimacy but more of a fear or unwillingness of commitment. Some men are like that. When they feel a relationship is getting too serious, too long they start wondering and expecting that the girl is going to start pressuring him for a proposal and want kids. it's really about immaturity. I'm sure this guy was happy to be with you, but he was purposely pulling away to move on to someone else. Some guys are like that. They are happy to have that status that they have someone to be intimate with but they are not ready for a serious relationship and will pull out of it before they are pressured to be tied in. The fact that this dude didn't properly end things is another sign that he's not mature enough for serious commitment with you.