Is it okay/normal to say mean things to someone's face because they rejected you?

This may seem like bait, but I'm asking a genuine question. This happened to my girlfriend where she rejected her former best friend (in a nice way…

This is why people ghost.

I date and I meet a lot of ladies who can’t take rejection without insults and harassment being given in return.

Yeah… it really is a shame. Like imagine being best friends with someone for 3 years only to turn on them because they didn’t like you back? Some people you can never be JUST FRIENDS with.
A lot of people only see other people in terms of transactional relationships. Once you stop giving them what they want out of you, they have zero use or interest in you.
Now that I think about it, I think my girlfriend’s friend was just using her to vent and eventually date and once she didn’t get what she wanted, dropped her. I mean, she was like 13 when this happened and now they’re 15 and my girlfriend is 17 (I’m 18), but still, she would say things to get negative reactions out of my girlfriend and threaten her and was quite the self-centered bitch