That's no longer standard - if it ever was. A no paramour clause can be added, but this generally lasts only as long as the divorce. Once the divorce is finalized it is very, very, very unlikely to be ordered. It is far too restrictive and seriously, when you think about it, almost ridiculous - what happens after 10pm that can't happen before? It's okay for the kids to be exposed to a new guy every night as long as he leaves before 10?

Dad can request temporary orders and request such a no paramour clause. The other guy's marital status is irrelevant.