Does the traditional British middle / working class version of marital monogamy HAVE to be the only way?
Ask the French, Germans, Italians or Spanish if it is, you would get a very different response to the strait laced Victorian version so many here in wonderful MNLand believe in try to live their lives by. Over time, people change, yet the societal restrictions we impose upon our British selves do not.
And yes, I speak as one who had strayed previously, but who chooses not to presently. And presently, there is a hint that my lovely wife might just possibly have been straying recently, and I'm reasonably sure she has in the past, but I'm not snooping, digging through phone internet records, not because I don't care, but because I know it'll blow over.
Might I stray again? I have no plans or intentions, but one never knows. However, we have over 24 years of marriage, a terrific life together, great kids, we are best friends, we have a lively interesting and active sex life and things are good.
So I can see where OP is coming from; not every one fits inside the same sized box.