There are many threads on this site about having guinea pigs and rabbits living together.
Some rabbit and guinea pigs do live together happily, however incidents do occur which can cause problems. The rabbit can get frightened and will do what comes naturally for him, which is to thump their back legs and will either injure or kill a piggie who may be next to the rabbit. Guinea pigs have been known to bully rabbits by plucking their fur, rabbits have been know to push piggies about including down stairs in 2 storey hutches and injure them. Male rabbits can if unneutered use the piggie as a mating object and either frighten or injure the pig.
Rabbits and guinea pigs also require different food types which will present a problem if they live together.
The guinea pig side of ARC so far this year has had 3 guinea pigs handed over to them who have had broken limbs following incidents with rabbits with whom they had previoulsy apprently lived happily with. ARC also frequently get reports of rabbits who have teminally injured piggies as well. It is for these reasons ARC will not rehome or recomend guinea pigs livig with rabbits, the majority of the national and smaller local rescues and the RSPCA also do not recomend this pairing.
Janice