I dont think that is a problem at all. I am married but the bedroom is more for sleeping partnership rather then sensual fun stuff. My vibrator can only please me so much and yearning for more, as long as there is discreetness and knowing your living on the edge and accept your fate, why not :)
I've been on both sides of the equation.
I tried to brighten up my sex life with my wife for years, with very limited success. She just wasn't interested, so I began looking elsewhere.
I ended my marriage, and she has no idea of what was happening, and I will never tell her, the only point would be to hurt her, and there is no need to do that.
I then moved onto a relationship with a woman who has probably had more partners than hot dinners, and I tried to get a lot of hot dinners into her.
She is unable to help herself, and it's not honest sex either, it's essentially repayment for grog, dope and gaspers.
I tried to talk to her many many times, but honesty and taking responsability for ones actions weren't her strong points.
We finished up 6 months ago.
I recently got an offer from an absolute stunner, who is being negected, bottom line is I said no.
In the end it's a personal choice, I'll live with mine.