should a guy have a condom on during oral sex??

I’ve never had oral sex or have done anything, but I have questions about this specifically .

If you are giving your boyfriend head, should he be wearing a condom cause of like STDS scares?

Will he find it weird if you ask him to wear one? Bc people always say you either swallow or spit, but I would find it gross to swallow cause of STD’s. But if you spit, do they hate that?