Apple Watch payment

Not sure.

For corporate accounts, some cellular providers, such as AT&T offer "Split Billing" were the company pays for the cellular plan, and the user pays the extra $10/month for the Apple Watch add-on cost.

You might check with the cellular provider if A) they support the Apple Watch, and B) if they offer "Split-Billing"

Then again, it is generally one $10 (U.S.) to add the Apple Watch. Perhaps your boyfriend's father would spring for that as well 😀

PS.

The GPS only Apple Watch can do Everything the Cellular model can do AS LONG AS your iPhone is nearby, where nearby is generally somewhere in the same moderately sized home. The Cellular model allows you to leave your iPhone at home while you go for a walk, run, bike ride.

So if you BF keeps his iPhone with him at all times, then he can just use the GPS only model, which is less expensive, and does not have any monthly fees.