Note: first marriages have the greatest success rate.
Here are some of the basics to help you get clearer on his situation…
He has no business jumping head on into another relationship with you or anybody else.
A man that has recently separated from his wife needs time to address the feelings of the marriage that has ended and where he goes on from there.
If there are kids involved, there is usually a discussion about how the wife is keeping him from him/her or how the wife was a not-so-great mother. It's just an excuse for the both of you to do what you are doing with each other without having to deal with the issues from that relationship.
He likes to talk about how he feels and how it's been so difficult for him.