Mollie, I agree with everything Logan said!! My dog Duncan was the second dog brought into the household and we dealt with A LOT of issues!!!! Jack, my roommate's dog, is so laidback and easygoing. It sounds to me as if that is Buddy! And Abby is the more rambunctious, aggressive, go-getter of the 2. Same situation I had.... The only thing I may disagree with Logan on is the feeding Buddy first and showering Buddy with attention first. And this is only because it sounds to me as if Abby will eventually be the alpha of the 2 from some of the situations you have described, such as Buddy no longer playing with his toys but Abby does....Buddy won't sleep in his bed but Abby sleeps wherever she chooses.....If you give Buddy extra attention of try to "force" him into the role of alpha, that is when fights will break out and Buddy will take the brunt of it.....We learned this the hard way in my house. Jack was attacked and bit lots of times before my roommate would finally accept that fact that Jack doesn't do much in the house w/o Duncan's approval and if you try to force him to exhibit alpha behavior, Jack will be on the losing end of a bad attitude from Duncan. Don't get me wrong the 2 of them seem to be very attached to each other but there was definitely an adjustment period.

If you feel Buddy is unhappy and it's making you unhappy, then find Abby another home. If you are very attached to Abby at this point and want to keep her, then just give it some more time and do more observing than interacting with the 2 of them.

I'm far from an expert on this or on much for that matter! but I have been through a similar situation and I hope my insight will be helpful.

Good Luck and please keep us updated!