In the Biblical sense how can Joseph be called Mary’s husband if they did not become one flesh?
He couldn't. Being a husband comes with rights and responsibilities.
Sex is one of them. That's what being *one flesh* is about and that is God's intent for married couples.
“In the Biblical sense how can Joseph be called Marys husband if they did not become one flesh?”
Apply that to Jesus and His bride. You might get an interesting answer either way.