I have a higher sex drive then my boyfriend 😐😳

My boyfriend is 18 and I am 19. We have been together for 3 years. We waited about a year and a couple months to first have sex. We finally did it and ever since then we have had sex quite often. Lately, we have only been having it maybe once every 2 weeks and its always me asking for it. I understand that stress can lower your sex drive, and he has been very stressed because he is going through finals and graduation is right around the corner. I have tried to back off and tell myself that he is stressed and I should stop being selfish. I have tried talking to him about it, and he always says he's too tired, etc. I don't know If I should just leave it alone for now, or try to keep talking to him about it, or just give it up entirely until he initiates it.

Advice would be greatly appreciated. ☺