If he's blackmailing you about this now what will he blackmail you about once married.
He's hoping if he can get you to study for 3 months you will convert - huh, who'da thought it, one high control religious group trying to convert someone from another high control group.
Anyway, call this a taste of things to come.
Tell him to he should not even have a girlfriend if wants to be reinstated back into his religion.