Need help with fwb situtaion.

Being doing it for over a year now, we communicate- i mainly text him and i ogranise most of the time he used to text up till of july of last year sometimes he does but yeah and we are coworkers so we try to keep out of work but talk well. and a few times in the past i have expressed i feel comfortable with him etc, he went quiet the last time i asked in person, and he was wanting causal for now. So idk if there a chance of something.

So I am fine with him, talking to other girls and he said he would try and keep me updated if they meet or they potential want to do a threesome with us. I told him, had talked to a girl on tinder if she was interested but turned out just wanted to be girls only no guy. He replied saying if you want to do that stuff by yourself you can. I said I wasn't interested in that dynamic with all girls and also added, more comfortable with doing one with him. He replied Fair, I asked if you don't mind (just double checking about what i said previously and he replied yeah that's totally fine. He does double check most times, saying if I am ok with that And on his tinder profile, he told what he put, by saying just looking for causal as of now. I doubled checked, if we were doing good and he said we are good.

Another thing that has me thinking could there be an opportunity for an open-relationship, cause some people at work have found out or have theories, he told me one person said something to him, he told me if they do ask or try to snoop in just say we're friends or something- well we are friends anyway. I am glad he didn't say we are just friends anyway. One more thing, a few months ago i was texting him one time when my best friend was around, and when i said I was with her he went abit funny saying Nice sorry but if ok just with us? Just prefer to keep this relationship between us I went I haven't (when I have). I asked if he done the same. He said yeah, he doesn't like talking about that stuff to others. I asked why this type of relationship or just general and he said kinda just in general do you think he is being trusting to me? He does let me watch him while he is on his phone and been to his twice. Is there a chance maybe since it's gone this far?