Sadly, I think some of what you are saying might be right, sometimes, Abitwobblynow.
DH and I had a rocky patch a few years ago and I became quite close to a fellow mature student at university. We became quite close and spent a lot of time studying and stuff together. There was a moment, nothing more, when I realised it could go further and cut the friendship dead there and then. At that point, no line had been crossed and I never wanted it to be crossed, but I know what you mean about it creeping up on you.
However, I'm not sure about the theory of "crushes, committees and golf" as exits though. Does that mean that every time we have an interest or a hobby or an involvement in something outside of our marriage/relationship/family that we are finding an escape route?
My DH and I both have interests outside of our marriage. Mine mean I spend time with other men (and women), his mean he comes into contact with other women (and men). Maybe other women find him attractive, maybe other men find me attractive
I'm not sure I could identify one though
! But it's not because we're trying to escape the difficulties of our marriage!!!
I don't think you can compare committees and golf/hobbies and interests with adultery!
Besides the people I have crushes on are often very different to my DH. Not better, just different.