When I meet friends of the opposite sex who are not single, I will try to invite their other half. If their other half is not available, it doesn't matter if we meet for dinner alone.
It's the same with boyfriends.
Eating and chatting, in our opinion, is a very normal social behavior between friends.
As long as the other person doesn't have an affair with himself, there is no problem.
Of course, normal doesn't mean there are no boundaries. There are rules for eating with friends of the opposite sex, such as not being too close, not staying too late and so on.
If you are a friend of the opposite sex who has ideas for you, then refuse decisively.
If you know that you are pure friends and your other half doesn't think so, be reasonable first and take your other half to meet your friends. The other half still disagrees, so forget it. After all, the feelings of the other person in love are the most important, and there are not so many right and wrong.