Why is john happy that bernard is not married to lenina?

John is happy Bernard and Lenina aren't married because he wants her for himself.

"Are you married to her?" he asked.

"Am I what?"

"Married. You know–for ever. They say 'for ever' in the Indian words; it can't be broken."

"Ford, no!" Bernard couldn't help laughing.

John also laughed, but for another reason–laughed for pure joy.