Put them in a tank with a grill in the middle. They can see and smell
and hear each other, but have no contact.
When you do breed them, introduce the female
into the male's side of the tank, NOT the male into
the female's domain.
Female hamsters are the more protective and
particular of their own domain
instinctively to protect their young. She will attack
him, and probably ferociously,
in other words.