I cheated on my girlfriend
Why did you cheat on your girlfriend?
There was no reason for it.
How would you feel if your partner cheated on you? I guess you'll be hurt. So you also shouldn't have cheated on your partner.
Who cares if my partner cheats on me? People always cheat anyways and get over it, so what's the point?
The point is it's immoral to cheat on your partner. If you're so insensitive about others feelings, nobody would want to do anything with you. You need to introspect and think about what you're doing.