Is to protect yourself. We live in the real world of STD's, HPV, HIV/AIDS and that is just reality.
If I had been smart enough to demand that my former BF use a condom, I wouldn't be where I am today. HPV with the high risk types and now left with a very ugly scar from having a genital wart removed.
Your BF isn't the one in the cat bird seat here. He is lucky to be with you and you have to set down the rules. You are right in saying he is probably spoiled going it the natural route but that is too bad. Using a condom can prevent a lot of heartache down the road. I know, I have and will continue to travel it.
Take care of yourself, first and foremost. It is a lot more than worrying about becoming pregnant. Believe me. That is just one issue.
Take care of yourself.
Bobbie