I could be wrong because misinformation about herpies is rife, but from what I know you can contract herpies on either your mouth or your genitals. Once you have contracted a strain, the other area cannot be affected.

Personally, if I had a partner I was serious with, I would purposefully contract their herpies on my mouth. this is because I find mouth ulcers to sound a lot less painful than vaginal ulcers, also I know of a lot more medications to help with mouth ulcers than gentialia. Also, it is more socially acceptable to itch/apply medication to your lips in public than it is your genitalia!

On the flip side, he may prefer to contract it on his gentialia as no one else will be able to see it, and he is less likely to pass it on to people, as most people kiss more people than have sex with them. I'm thinking about kissing family and children in a platonic way.

Have a discussion with him before you have sex. Condoms are not very effective in preventing herpies as it spreads through skin on skin contact and his base/balls/gooch may still make contact with your affected area.

If you are both serious about each other and in it for the long run, it's inevitable he will also contract it, the biggest question is where.