Is going off birth control the reason our sex life started to suck?

Looking back, I think that our sex life started deteriorating once my wife stop using oral contraceptives and we switched to only using condoms.  No, not because I don't like condoms.

There appears to be a lot of research out there that suggests women on hormonal birth control tend to be more attracted to "team players" who may have "less masculine" features, while women not on hormonal birth control are more likely to be attracted to "rugged masculine males"--and the negative baggage that society's conception of "masculine" brings, such as being less like to do his share of the chores and more likely to cheat.

Well, I am certainly a team player.  I do more than my share of the housework.  I have been dependable even when my wife hasn't reciprocated.  I have not acted on any attraction I felt towards other women--though my wife has expressed jealousy.  (For example, when I was having lunch with a female colleague while I was out of the country doing doctoral research while she later admitted that she kissed other guys and went out dancing.)

And I have always been "less masculine"--often the reason why I was beat up in school, for example.  I have seen not buying into machismo as one of my assets.

In 2004, almost two years after our son was born, I got a really bad prostate infection. The doctors asked me when was the last time I had intercourse.  I couldn't remember.  As our son got older and more mobile, my wife used privacy as an excuse to avoid sex--he is still awake!  Then we had our daughter in 2008.  More of the privacy excuse.  Then more of the oh I forgot, oh I am too tired excuses (the ADHD factor kicking in.)  I have been waiting and hoping for things to bounce back.  Maybe they never will?

About 2 years ago, I think, we were having so little sex--she kept making promises that went unfilled--that I asked her if she really wanted monogamous relationship.  She accused me of "threatening" her if she did not "perform" her "wifely duties."  Yes, she actually said, "wifely duties."  Gee, that made me feel attractive.

Monogamy does not mean celibacy.  My agreement to not have sex with any other than her is dependent on actually having sex with her.

I have been feeling more compelled to cheat, and my therapist has subtlety encouraged me do so.  (FYI, my therapist is a woman and she has directly observed how my wife and I interact.)  I haven't for three main reasons.

1) My integrity--I am an honest person.  I keep my promises.  I stand by people.  I don't want to see myself as dishonest.

2) If I did, my wife would become extremely jealous and not allow me to engage in the volunteer work that I do, which is very important to me.  She would assume every time I traveled to do volunteer work that I was having sex and therefore I should not go.

3) I honestly don't have the time for an affair!  I would have to give up something else that is important to me, such as the volunteer work.

I guess I also afraid of things like having to explain embarrassing medical problems, not knowing how to date (I was never good at it in the first place), etc. Looking back, I also had a tendency to become too invested in a relationship too quickly.  I am afraid of that happening again.