I breed and show Dalmation guinea pigs. I have a beautiful sow who needs breeding with, i have run her with 2 breeding boars at seperate times and she wont get pregnent so im going to put her with a Aby boar, if anyone can get her pregnant he can, he is a super stud. All though the babies will be cross bred, im hopeing that once she starts having babies she will carry on with my other boars.
It can happen that a bitch sees her running mate as a friend, not a mate, so will reject him Doesn't happen very often, but it does happen ;)
Your guinea pig might not be able to breed. We took on a female that had been left with males, but never had a litter. She spent the rest of her life living with a male and never had young :( Just one of those things. ;)