I wouldn't say so. Or, to be more exact:

Because at some point... I'd want the relationship to change. And it's not fair to him because we would have agreed to be friends, so it would be unreasonable to get upset with him if he was hitting on other women or didn't want to stay for breakfast.

No jackass.

whenever I got a little bitchy with him it was all "you're pissed because you want to go out with me, right?"

Jackass.

Because it can often be more complicated than that. I am big on bright clear lines of expectations, but I can totally see a guy (or girl) making the FWB seem like that's the situation because he (or she) isn't ready for a relationship, not that they don't want a relationship with a specific person.

There was that Dane Cook/Jessica Alba movie.

Yeah! I think that's what I was thinking of. I knew that exact concept had come up recently.

Because it can often be more complicated than that.

true. But if everyone has been honest*, none of these situations mean that the guy is a jackass.

*admittedly, sometimes feelings change in the course of things, and what you agreed to isn't necessarily what's happening.

To me, FWB implies I don't want a relationship with you and it's hard for me see how that doesn't turn toxic at some point.

One of my FWBs was an issue because he basically wanted a girlfriend, except when he didn't. He would call to talk about his day, pay for dinner, make me breakfast, cuddle, etc. But then when he felt like having sex with someone else, he did and fell back on the "we're just friends with benefits". I was confused because I thought he wanted our relationship to change with all of the boyfriend behavior, while he thought that we had a defined FWB relationship so he could do what he wanted.

To me, FWB implies I don't want a relationship with you and it's hard for me see how that doesn't turn toxic at some point.

I don't think it necessarily means "I don't want a relationship" so much as "I don't want a monogamous boyfriend/girlfriend (or boyfriend/boyfriend, girlfriend/girlfriend) relationship with you."

It's not something I ever did but I think there are people who can have this sort of relationship without it turning toxic. It may not be a long-term thing (but who knows) but I don't think it, by it's nature, needs to end with bad feelings on either side.

Oh, I'm not referencing any particular people, just the tumbleweeds blowing through my love life on a general basis.

My sistah in the weeds. It's dry and dusty out here.

To me, FWB implies I don't want a relationship with you and it's hard for me see how that doesn't turn toxic at some point.

Not necessarily. I had a friend, not a close friend just a friend, that we both knew we weren't right for a dating relationship, but we had great chemistry. We had a FWB understanding that we were both cool with. Never turned toxic. I started dating someone, it became serious, and we backed off the B part. He started dating someone. Then we lost touch.

One of my FWBs was an issue because he basically wanted a girlfriend, except when he didn't. He would call to talk about his day, pay for dinner, make me breakfast, cuddle, etc. But then when he felt like having sex with someone else, he did and fell back on the "we're just friends with benefits". I was confused because I thought he wanted our relationship to change with all of the boyfriend behavior, while he thought that we had a defined FWB relationship so he could do what he wanted.

This! I've seen this a lot. Even worse, I've seen the dude get mad when she said she had a date!

Most of mine have been friends that occasionally I'd want to get horizontal with someone and liked and trusted them just fine, so I did. Only once has that ever become an S.O. and then we got married.

Maybe I'm just cynical, but it seems like the kind of understanding that works in theory, but in practice odds are one side or the other will change to (or entered with unvoiced) expectations of a monogamous relationship.