What are the things that make an existing relationship worth choosing over the desire to be with someone else?

[tesla8520]

From a post by a woman who feels attracted to another man while she's in a relationship with her husband, who she feel is the right man in every way:

I've been married to my husband for a year and I love him more than anything; he's the right man for me in every way. However, lately I've noticed that I'm starting to think and fantasize more often—something I almost never used to—about what sex might be like with someone else, for example, a colleague of mine with whom I work a lot and who is a very attractive man. I'm basically a pretty and fairly good-looking woman, so I get a lot of compliments, which further amplifies these thoughts. I believe in marriage, so I don't know why I've started to feel a little scared by the thought of never again experiencing that new feeling you get when you're with someone for the first time. Is this normal? Is it some kind of "door-closing" panic? What can I do about these thoughts?

What she's saying is simply normal.*
We all feel attracted to other people, even when we're already in relationships.

That said, the choice is always ours.
But what is that choice based on?

Certainly on how we feel within that relationship.
That relationship must have elements that make it worth staying.

Here, we get to the heart of the matter.
If you've ever found yourself in this situation, you had feelings or an attraction for someone else, but you were already married or in a relationship, and you're a man of values, what were the elements that made you stay?

The elements of the relationship that made you realize it was simply worth staying, or better yet, in a negative case, leaving.


*: for many sosuavers here, emotional detaching from a woman it's a bad sign, and most veterans here would see that like a "disrespect" behaviour, but actually human nature programmed us to feel that desire to someone we feel compatible with, and most people would say that if you give it "time", the "flame" will shrink, and this desire will pass.