More advice please

Dear Nairalanders, let me just go straight to the point, I'm Married and currently with my wife, she is presently 3 months pregnant, and from day one we found out she's pregnant till date, she doesn't allow we have sex with her because she is not feeling fine, we both sleep naked as usual with a great urge in me to do it, but I can't even ask her because the last time I didn't her response was that I'm not been considerate, that despite her condition all my interest is sex, I've endured this for three months, and right now I'm been tempted to cheat, what do I do