There is a sharp difference between fantasizing about other women (many men do, even if they say they don’t….we usually say we don’t to save feelings) and getting calls from them at midnight. I would be worried. I would NOT, however, do something silly like give him an ultimatum (her or me, etc). Just tell him that it bothers you that he spends so much time speaking with her and the times that he does it at are concerning as well.

If I could tell about 99% of people on this board one thing, it would be TELL PEOPLE HOW YOU FEEL. You would be surprised how many problems are solved and started by doing and not doing that (respectively).