Ask him. I've had two of my partners actually trim my hair, so they got it to the length they preferred, and recently I've started sugaring (a less painful alternative to waxing). Just keep these two things in mind:

1. It's nice to please your partner, but your pubic hair grooming should definitely feel like your own choice and not societal pressure.
2. Your partner should be ok with whatever you decide.

While my current partner was pretty much ecstatic when I started sugaring, he never had a problem with a full bush, either. I think as long as there aren't loose hairs, not trimming at all isn't a big deal.