Is flirting ok?

So my SO and I have been dating 7 years and like I see him flirt with his coworker even tho he says he doesn’t but whatever fine. Do you guys think it’s ok to flirt? Like as long as you come home to that person at the end of the night? Like he isn’t going home with her and he’s still with me. So like is it ok? So many people have told me “you guys are like married it’s fine if you both flirt with other people don’t be mad because he comes home to you either way and in every relationship that happens so don’t trip” idk I’m actually confused.. like I don’t do that nor do I care too? Idk