You should not be converting to marry your boyfriend. Changing one’s religious beliefs is a serious matter and concerns one’s relationship with God. You should only convert to Catholicism if you truly believe that Jesus Christ founded the Catholic Church and that therefore to enter it is the best way to serve Christ. If you don’t sincerely believe that, you should not become Catholic and your boyfriend should not be pressuring you to do so.
What you can do is to study what Catholics believe and see if you honestly come to share Catholic beliefs. If you reach the point where you would convert to Catholicism whether or not you ever married your boyfriend, then and only then can you become Catholic. If you cannot accept Catholic belief to be true, then you and your Catholic boyfriend should part so as to free each other to find a spouse who shares your respective religious beliefs.
