I don't think you'd be asking if you weren't questioning the relationship already. People can obtain divorces, no matter the emotional/financial aspects. If someone truly wants to be another person, they will end the relationship they're currently in. Any number of people love selfishly and don't want to make hard choices or be held accountable. If you want to see how he really feels, end the relationship with him and tell him he can call you when he gets his divorce. He's cheating two children here--unless his wife knows about his affair, he has to sneak around to establish any relationship with your daughter. As long as this man chooses to stay in his wife, your daughter has an occasional father, someone who can be counted on to deny her existence to his family and friends, to not pay child support. Your daughter will be curious about her dad's other family--and feel hurt and resentful of the time he shares with them (his other child will feel the same way about you and your daughter.) Both kids are going to feel second place to their father's needs.