These situations strike me as odd. Can't these woman tell that their boyfriends/fiances/husbands seem to not be interested in sex with them? Granted, sometimes things happen and attraction fades, but how can these men have tricked their girls FROM THE START???
Unless, of course, they really are attracted to women too, in which case there is no excuse for their affairs in any event.
Research i've read, indicates that a majority of so-called "homosexual" men, and an overwhelming majority of so-called lesbians, have successfully copulated with members of the opposite sex at some point in their lives. In other words, they are pefectly capable of getting PHYSICALLY aroused and HAVING SEX with the opposite sex -- they just don't FALL IN LOVE the opposite sex.
Which is another way of saying, homosexuality is an emotional problem, not an innate sexual orientation.