I’m not having an affair.

[Expectingaflamimg]

I’m married with DC, he’s not.

I’ve fallen for someone, we’ve discovered that he feels the same after a work night out, but I’ve firmly refused to take it forward, even though I desperately desperately want to.

I am making the right choice morally, the right choice for my DC. It has made me realise that I need to end my marriage, I will work towards that I’m a planned and honest way. This is the right and decent thing to do.

So why do I feel devastated?

Why is it “end the marriage” and not “fix the marriage”?

Because OP has made it clear she won't have an affair. If she starts a new relationship, it will only be after she's ended her marriage.

Yes, but why is her first thought to end the marriage and not how to fix it. Given it appears to have come out of the blue.

Cognitive dissonance soup
And a very strong cultural narrative that being in love with two people is not possible and must mean something is fundamentally wrong with your marriage.

It annoys me a bit because there are so many models of human relationships, including ones where a person can be married to several others (more usually men than women). So I know logically it's possible to love two people but it us so frowned upon in western culture.

Steady on. People can have very powerful crushes on others whilst married. These crushes pass and fade. It’s what you do with those feelings that matter.

As others have said, separate the two. What is wrong in your marriage? Is it fixable? Do you share the same goals and values still? Is he kind and decent?

Don’t throw it away only because of a crush.