Aly, I have the same problem with Perry and Daisy they act like a pack of two and we wanted to try another pup in the house but
they just won't accept one. Give it a little time, Lolly is really still adjusting herself and when she really feels secure, she may have a change of heart. He is a little sweetie and I hope it works out for you, but if not I'm sure there will be one who will fit right in.
Jackie