I have some in common with OP but want to mention them my way:
Loneliness: We're social creatures. It hits me very hard to be lonely. After a while, i feel like i need a beloved one like air to breathe.
Cheating/Leaving: I don't like to destroy such a precious thing like a relationship, that once had been firmly confessed, its the most heartbreaking pain. I know, people have their reasons for it. But for some of us it leads to loneliness... i personally REALLY won't
ever miss that one for sure!
Unfairness: thats how the world works sadly but nevertheless, sometimes it feels like:
"I tried so hard and got so far, in the end - it doesn't even matter"
Lookism/sexual attraction: Beauty in its variations is very attractive, i always admired alot of people. But nowadays it got too important for so many people, especially because of social media 'competitions', some neglect even their life respectively live for that...
Competitiveness: its always like that but in times of technology progress, artificial intelligence and overpopulation (sry, idk whats that in english?) its hard for alot of people to compete. Imagine it will just get worse.... it would not be an issue if society management (?) were all good. Many people cant have a dignified life almost everywhere now. Thats absurd, life should get better...
'Distressing' emotions: Yeah... i would just not miss them of course. I only like positive ones even if they are quite rare