Have you ever had to "break up" with a FWB?

Sort of. He just stopped talking to me when I told him I had to stop because he was wishy washy and making me crazy.

I never had a FWB. Having sex with friends is getting married. So I married them

My wife had to eventually break up with all of her FWBs in college, but they remained friends, just with no benefits. In fact, one of them called yesterday and they had a nice talk. She warned them that they would get dumped if they got serious about the relationship.

Yes I have. It was messy as he wanted to pursue his ex who loved to cheat on him. And I wanted to remain friends

True. Undefined relationship are hard to end. Usually your friends and partner just learn to live with it. Look at Prince Charles and Camilla. No one could clearly define what it was in the beginning. But they all knew something was going on. So ... 🤷‍♂.
I don't think you can break it up without ending the friendship. But leaving in a different city, country, continent can help.

That kinda defeats the purpose, don't ya think?

Never had one 🤷‍♀

Yes, often. Usually because there is suddenly too much emotional attachment? Or because they have found a more permanent relationship. I have been in a space where we just get bored of each other

I've had to

Yes

I never had a FWB but I have broken up with boyfriends by just pulling away
No need for a hard line breakup just don't call, don't text.
Be vague about your plans and if they call or ask about anything just say that you are busy or spending time with someone new or whatever.
Or just not feeling it lately.
This usually gently ends things.

Actually it was pretty easy for me I just quit texting them after a while they just drifted off

Many times, but I've never had a respectful one or one that didn't like to blur lines and confuse me