That is sweet but they shouldnt be living together, they have different dietery needs and once the bunny gets older and hormonal the guinea pig could get hurt, there are alot of guinea pigs handed into rescues with fractured pelvis' due to the rabbit trying to mount them. There is also a danger of cross infection. Bacteria that may cause no symptoms in a rabbit may cause serious illness in a guinea pig. At 8 weeks they are very sweet but its a disaster waiting to happen im afraid.

I hope you dont take that the wrong way, i kept a guinea pig with my bun when i was little becasue we didnt know any better, the guinea pig died from a bacteria carried by the rabbit.