It's not cheating. BUT it isn't good behavior and is disrespectful to your partner.
But there is also a lot of variance too. It could be something fairly innocent, like flirting with a cute waiter or something more serious like bordering on (or actual) emotional cheating.
I think most people who have been in long relationships couldn't say they've never flirted with anyone at all that whole time. Mostly, I think it's up to you to be aware of where that line is drawn... what is and isn't okay, what would upset your partner / is disrespectful to them.
But there is also a lot of variance too. It could be something fairly innocent, like flirting with a cute waiter or something more serious like bordering on (or actual) emotional cheating.
I think most people who have been in long relationships couldn't say they've never flirted with anyone at all that whole time. Mostly, I think it's up to you to be aware of where that line is drawn... what is and isn't okay, what would upset your partner / is disrespectful to them.