Tannaog
Have skimmed the thread so sorry if this has been said before.
My dsis experienced something similar in her marriage.
Her (now ex)DH (computer geek) met a girl in chatroom, she was coming out of a relationship with a twat. He talked to her all of the time, going to bed late as he was online talking to her. My sister had it out with him on more than one occasion how he was making her feel and not giving enough to the marriage, too tired from being up all night, all brushed under the carpet, it's nothing serious blah blah blah.
Scroll forward a few months he's now at my parents with my sis and their young family, he's still talking to the trollop due to move house from one end of the country to the other, but instead he finishs with my sis by email, saying now one else involved! Unfortunately for him he failed to delete his brosing history we now have copies of chats where he told her how much he loved her and ones where she encouraged him to leave dsis (all on my parents computer
!
Sscroll forward a few more months he's left his home town to move in with her and her dd.
(although thankfully he's now been booted out! (yes I am a biased big sis).
I don't know whether any of her story rings true for you but I personally would be VERY VERY cautious. The emtional involvement of talking to someone else all the time sharing hopes and dreams, and the maons form bad days etc are what I consider to be a part of marriage.
If he's talking about her all the time I would be very worried, and I think I would be asking about the state of my marriage...