You have to ask yourself and your boyfriend this question. We have no idea what would happen to you.
I recently asked my bf to stop having sex: even though we practice VERY safe sex he always panics about silly things such as if there was a leak in the condom and even if my period is late! what could happen to our relationship if i stop sex?
So each time you have sex he worries about getting you pregnant even though he is wearing contraception. I think you need to discuss why he feels this way and what you can do together to alleviate fears. No contraception is 100% safe. However, using two types of contraception like the pill and a condom would lessen you odds, but again this is something you need to deal with together because each choice has it's own implications, obviously the pill or injection can have side effects for you, and requires commitment on your part and trust on his. Maybe going to the family planning clinic/association to discuss contraception would help.
Well ... At the very least ... He would resort to masturbating. Lol
Well, unless you both agree to it, your relationship will definitely change.
But we don't have enough information to make an intelligent guess as to how.
You already know what's gonna happen he's not just gonna stop wanting sex