Scientifically speaking should humans actually cohabitate or should even married couples live separately? Was cohabitation even the norm before religion made marriage the default for long term relationships?

The thought honestly disgusts me and I definitely didn't enjoy it when it was even short term, there's always checking in, nagging, never having any sense of privacy, passively annoying each other all day etc. It makes you go from looking forward to seeing your spouse to looking forward to being alone