Culturally, no man was allowed to just randomly spread seed due to not knowing what will pop out and who it will end up with.
It was looked down upon because if a man slept around, he'll never know where his child is.
If a woman does, well, she's the one who gets pregnant.
The man is in a position where a child could exist but all mom has to do is tell him that the baby died in a miscarriage. He'll never know if the child is alive if mom doesn't contact him.
One night stands left kids with no fathers since fathers never knew they existed and would leave before father and mother knew they were having their first child.
It could be on bad or good terms, but it was looked down upon because she could have your child.
She could abort your child and you wouldn't be there to protect the unborn baby.
She could abuse the child and you aren't there to stop her.
This is why it is seen as stupid in Suman to sleep around as a male, you could end up having a child and never be there to protect them. Your future kids could accidentally marry a sibling you had no idea was your child. YOU could accidentally marry your child.