His mom would be very upset but my WH doesn't want her to find out.
It would probably be a good idea if he told her. The more people who know, the more people to hold him accountable. And I agree she will be upset. I would be upset too. But I would hold my son accountable.
I suspected you did live together because your husband has a very unique renter's mentality that comes from living together. When newly married couples have trouble this soon, this is almost always the reason why. He believes he is entitled to look elsewhere when his feelings ebb. Renters believe that you might be right for me today but wrong for me tomorrow, based on my feelings.
Couples that live together before marriage have an astronomical divorce rate becuase of the poor habits picked up while living together. This is part of the dynamic that is at play here:
Living Together Before Marriage: Compatibility Test or Curse? From Harley's book,
Buyers, Renters and Freeloaders:
Freeloader is unwilling to put much effort into the care of his or her partner in a romantic relationship. He or she does only what comes naturally and expects only what comes naturally. It's like a person who tries to live in a house without paying rent or doing anything to improve it unless the person is in the mood to do so.
Renter is willing to provide limited care as long as it's in his or her best interest. The romantic relationship is considered tentative, so the care is viewed as short-term.
It's like a person who rents a house and is willing to stay as long as the conditions seem fair, or until he or she finds something better. The person is willing to pay reasonable rent and keep the house clean but is not willing to make repairs or improvements. It's the landlord's job to keep the place attractive enough for the renter to stay and continue paying rent.
Buyer is willing to demonstrate an extraordinary sense of care by making permanent changes in his or her own behavior and lifestyle to make the romantic relationship mutually fulfilling. Solutions to problems are long-term solutions and must work well for both partners because the romantic relationship is viewed as exclusive and permanent. It's like a person who buys a house for life with a willingness to make repairs that accomodate changing needs, painting the walls, installing new carpet, replacing the roof, and even doing some remodeling so that it can be comfortable and useful.
Renters believe Our relationship is temporary. You may be right for me today and wrong for me tomorrow.
Buyers believe We are together for life.
Renters believe Our relationship should be fair. What I get should balance what I give.
Buyers believe We both contribute whatever it takes to make our relationship successful.
Renters believe As needs change, the relationship may end if needs are difficult to meet.Buyers believe As needs change, we will make adjustments to meet new needs.
Renters believe Criticism may prompt me to change if it's worthwhile for me to do so.
Buyers believe Criticism indicates a need for change.
Renters believe Sacrifice is reasonable as long as it's fair.
Buyers believe Sacrifice is dangerous and to be avoided.
Renters believe Short-term fixes are fine.
Buyers believe long-term solutions are necessary.