I understand and would be disappointed too. Personally, I think the best fostering situation is one where the animal is placed with someone that is close enough that the original owner has plenty of physical contact/visits. I know people who foster pets and yes they love them too, but understand that their home is not the animal's "forever" home. Giving up a pet is a very gut-wrenching/hearbreaking decision. Several years ago, I had to do the same with my 6 month old Golden Retriever, so I understand Beau's mom's desire to have the opportunity to reclaim her baby if at all possible.
Hang in there, you're right another baby is waiting for you