Most Helpful Guy
I think that maybe you can give him other thing to symbolize.
That's what i prefer too, i dont like to feel a ring in one finger, it's not that confort and good...
Most Helpful Girl
Well if he find promise rings stupid why not get him something else that he does like? Keychain, bracelet, you two as bg photo on his phone or some? I have no experience doing something like that. So these might be childish ideas.
If I were you I'd ask him what he would like to symbolize your commitment.
Then again: you're a couple isn't that enough to symbolize your commitment? If he wasn't commited to you then you guys wouldn't be dating... right? ( well let's consider that he isn't cheating lol xd )