I've never understood how to be a bad partner. Like I know what others do that fuck things up in a relationship, but to me it's just painfully obvious how to be good to your partner.
Can you tell me how to be good? You cannot.
Can you tell me how to be good to your girlfriend/ fiance / partner? You cannot.
Can you be good to your partner? You cannot.
Humans are incapable of good, true good. For they know not what it is and neither do they have the knowledge to direct their own will.
The secret is out there but you don't have it. You are teaching people how to grow hair when you are receding. It's not convincing.