Nobody can give you a firm answer to this problem in a marriage. I guess I'm lucky and get something once a week.
I can get my extras from porn. I cheated once and it led to us swapping but since then we havent swapped.
Unless she says yes to you seeking sex elsewhere you are still cheating.
Personaly I would hate to be found out and break my wifes heart because even the lack of sex I love the women I married.