His profile mentions he is separated so I am going to give him the benefit of the doubt and say he is going through a divorce (unless of course you know otherwise).
I'm on board with the others, giving the benefit of the doubt, that he really is separated.
I mean there are other sites available (Ashley Madison) for married ppl who want to have affairs and it's free. I'd like to think ppl are smart enough to research if they want to be sneaky. However, we all know it's not the case.
Does he not know that you can see who is checking you out? If you know them and he is married and he knows that you know, it seems odd that he would out himself to you at all.
I would be so so tempted to send him a little message; "Hey, what happened with wife? I'm sorry to hear you have separated." But, that's wrong, isn't it.