In response to:
I don't think anybody could just say no, and that's that, no argument. There are situations where it's perfectly possible to love someone yet have sex with somebody else.
Sometimes, particularly in a long relationship/marriage, love and making love gets lost in all the day to day dramas, and being human we need a little loving from time to time. I'm not saying that people actively go looking for it, unless you are a serial philanderer, it can often happen accidentally when you are at a low point. I would go further and say that it may not always be just about sex but to have a feeling of intimacy with somebody and a confidence boost.
I have read of people with partners who sadly are unable to make love for a number of reasons and such are their physical needs, they have to find that satisfaction elsewhere. It doesn't mean they do not love their partner and sometimes they have come to a mutual agreement about it.
If sex is not important to you then all is well, do not judge people for whom it is important and try to recognise the difference between, as I said, serial philanderers and others.
I'm not saying that people actively go looking for it, unless you are a serial philanderer, it can often happen accidentally when you are at a low point. I would go further and say that it may not always be just about sex but to have a feeling of intimacy with somebody and a confidence boost.
I believe that if this type of feeling is coming up when I am in a "committed" relationship with the promises that entails, I need to do some serious re-examination of what is happening in said relationship.
I have to say this - the image of tripping and 'whoops there you are...' is so funny - I have never been able to have sex accidentally, and while I can agree that in cases of inability on the part of one partner to perform at all an agreement can be reached, if fidelity has been promised that promise should come before personal desire.
Lacking sex with a partner is not the same as lacking food, water or air.