No, monogamy is a lifestyle (choice) and not a genetic code.
As a heterosexual male there was never a moment that I "decided or chose" to be attracted to women. It was in my (natural) genetic disposition to be attracted to them.
Monogamy involves (promising to be faithful to someone) and later betraying them. Intentionally deceiving someone has nothing to do with one's orientation.
If a person simply wants a "variety" of sexual partners there are plenty of people willing to be "booty calls", "friends with benefits", "no strings attached" or will even have sex for money. There are "swingers" and people who are into having "open" relationships.
Therefore it is not necessary to pursue relationships with people who are looking for a "monogamous relationship". That would be the equivalent of a sexually oriented lesbian pursuing relationships only with men for fun. Cheating is a choice not an orientation.