Nope, sorry, they really should never ever live together. Unfortunately, a lot of people still think it's safe.
If a rabbit gets spooked by something they may thump, kick etc, and kill the Piggie. Not on purpose, but piggies aren't very big.
Piggie food is not good for bunnies, bunny food is not good for piggies at all. They are totally different animals and have different dietry requirements.
Although they seem happy, the bunny must be stressed, bunnies groom each other to show affection, and may groom the guinea pig and be frustrated when it doesn't groom him back.
I won't go into more detail here, but
here is a more detailed page. Please separate them, guineas should live with at least one other of their own kind, and rabbits to best in opposite gender neutered pairs too.