The odds of getting HPV via safe sex is 50% but this doesn't mean that it occurs in 1 out of 2 sex acts. It takes considerable amounts of sex to get infecteted. However when you factor in 100+ partners, the odds are certainly good that he has been exposed to it, even with safe sex. And the reason is that condoms don't cover a lot of genital skin. They don't cover the pubic area, thighs, buttocks, scrotum or even the base of a penis. And HPV can be on any of these areas. This is why it is almost impossible not to spread it unless people have sex fully dressed which no one does. And since the base of a penis would still be exposed while fully dressed, even that would be a risk.
Having said that, if you have had sex with 4 or more partners in your entire life (and this includes oral sex, rubbing of genitals, etc), there is a risk that you already have it but the risk is not as great as someone who has had 100+ partners. If I was you, I would insist on having safe sex at least until he gets a 8 or 10 panel test done to make sure he doesn't have any STD that men can test for and for you to get tested too. Compare results and understand that getting HPV is as inevitable as getting the common cold from contact with someone who spreads germs. If you are under 26, get the vaccine.
Many people go thru college sleeping around. They get tested for STDs and hope for the best. When they meet their life partner and get married, the college life can haunt them later on. Women can get a positive result and their first response is to assume their spouse has cheated on them. But the infection could have occurred pre-marriage and so this is why monogamy is rather important even when people are in college. Every partner you sleep with is a risk, safe or not. The only 100% safe sex is no sex.