Why would he say this?

So i have a FWB and we have been doing it for the past 3 years. We've both admitted that we fancy each other but neither of us are ready to commit for different reasons. Weve also both dated other people in the past 3 years (neither of us have got past a month with anyone else) and its just not been an issue.

So I got invited out on an unplanned last minute night out on Thursday and I bumped into a couple of old workmates in a bar, I haven't seen them in about 5 years so obviously we had loads to catch up on. It got onto the subject of my love life, i was with a guy when they last saw me and now ive been single 4+ years. I said i had a FWB but it wasn't serious - just at that moment my FWB and his brother came into the bar. He saw me and came straight over and introduced himself as my partner of a few years and kept telling people he loves me and he is glad im his lady.

Obviously we aren't partners, we dont date, we just have sex a few times once or twice a month, its only the 2nd time ive ever met his brother - who seemed equally surprised by it - and it just made me feel a bit awkward tbh. Especially since my friends all thought he was a good match for me.

I know he had been drinking and was a bit drunk, thats the norm for him. We kissed a few times but we didn't even go home together coz his brother went off to look for his mates and my FWB followed him. I later got talking/flirting with another guy but I didn't do anything with him coz my FWB had confused me.

I just don't know why he would tell people that?

Does it mean he actually wants us to be partners?

What should i do?