It's easy to love a child he hasn't had to do anything for yet. He hasn't had to get up to a crying baby in the middle of the night. He hasn't been confined to the house because a baby can't be left alone. All he knows is that the child's mother is "crazy." And now he visualizes you caring for this baby. It can be hard enough to love a child who is your own. You're not going to want to be tied down by someone else's kid. He's desperate to find a girlfriend who'll put up with his situation. That could explain all the attention he gave you for a month. Grooming you to accept this.