If he is not bi polar or borderline personality perhaps he is screwing around.
Goes back and forth with his guilt etc. Perhaps he is struggling with something else sexual. If he likes having sex with you remind him that you actually have to "want" to have sex with him and his attitude is taking the wind right out of your sails. This phrase really woke my husband up...as if he could treat me like a common citizen and then expect me to just give it to him because I'm his wife.
I personally am not against a little snooping if there is real cause for suspicion. Most people will think that is just awful advice, I don't give a crap.
The more I read this forum the more I see wives like myself are struggling with husbands who have a sense of entitlement, expect wives to put up with everything and expect nothing less than a whore, babysitter, house wive, Stepford wife with a smile on here face who keeps her mouth shut.
The more I assert myself in this marriage the more my husband is convinced I have issues that need medication. There was a time I was on Prozac after the birth of my second son. My husband really liked the fact that I complained about nothing. I recently read an article in Oprah magazine about being medicated to the point of being overly compliant.