Sex is very important to any healthy relationship. However during her later months of pregnancy some women (not all) don't want anything to do with it. I do believe you should go ahead with marriage counseling now instead of later. I think that would be your best thing to keep away from an afair at this point. I would stop the coffee breaks with the other woman right now. Most relationships stem from casual encounters especially when there is discontent at home. Congrats on the near arrival of your son!