Hi Victor:
I'm not trying to justify anything at all, but I guess my point boils down to the fact that life changes...we change...and sometimes we need something from another person - say of the opposite sex - that we don't receive from our spouse.
Unless you find an exchange on emotional level with someone a betrayal, I don't see anything wrong with connecting with someone on that level.
Love has many faces and can be experienced in many ways other than within marriage. I think this requires an open mind and freedom from religious restraints.
I know this is a difficult one to get your head around.