Replying to I hate my friends girlfriend

shes a bitch. my friends and i have started a secret operation to try to break them up. we are all good friends with him but it seems like shes changing him. there relationship seems alot more physical then anything els.

so far we havent done anything big. weve just been giving him the message that we really don't like her.

but shes off at a camp for a month and we are planning to write a letter to her trying to break them up

so leave some advice as to what we could to brake them up. we have all summer long to try. so please, help my friend