If you are so lonely that you are willing to date someone who is still married, then you are compromising God’s best for you.
It’s not to satisfy loneliness or have someone meet your needs.
When he comes to see me in the evening, he ususally rushes out again soon under some excuses (has to go back to work, has to take his sister from work etc.).
When I told him recently that I doubt if he's actually separated, he seemed to be frankly hurt (not upset).
I prayed against pride that would keep both he and his wife from seeing truth.