what is considered cheating?

so I'm wondering on people's opinions on this: at what point of looking at other people is it considered wrong when you have a partner??

some people don't want their partner making eye contact with people of the gender they like. some don't like them just talking to them. some are okay with friends. some are okay with them thinking another is attractive but still love the original person. some just think thoughts like " oh well they're attractive and stuff. they wouldn't be terrible if my partner leaves me. but I definitely still love and want my current partner more". some just full blown start hugging and touching the new person. and some even kiss.

at what point is it considered not safe for a relationship or cheating???