What’s stopping you from asking him out? Is his SO a wife or a girlfriend? You never met in person so you are just someone he likes chatting with. Could it be more .. maybe. He is with someone else though and you never met him in person it’s just fantasy atm. He isnt connecting with you - you are connecting with him. He enjoys the conversation and that’s all it is right now. If you want more tell him. If he can’t give you more and this is driving you crazy then tell him. Be honest in your relationships - if they can’t handle you as you - why are you even sticking around. Be yourself and don’t make yourself crazy over someone who is with someone else. Do what’s best for you. Go for it and then see what’s next.