We got our new puppy about a week ago (See "The sheltie I actually brought home!") I was going to wait to name him, but my husband asked if he could name him "Buddy". I'm so excited that my husband loves him, that I agreed immediately. When we were at the breeder's they said that he was the one that liked to cuddle, and at first that was how it was. After a few days the sheltie pup and our bichon became very close friends. Now they don't want to be with us, they just want to play with each other. Today I separated them so that we could play with Buddy, but all Buddy wanted to do was look for the Bichon. I am considering separating them for longer periods (maybe 4hours a day), in order that the sheltie isn't ruined as a pet. Any suggestions on how to handle this?

Give it a try . Have you tried playing with the both of them as a team? Try playing fetch with them or just chasing each other around. That is what I did when I had a Multiple animal home. They learned to welcome each other into games and when they tuckered out it was quiet time for me.
You have nothing to lose. But I'm afraid to say sounds like the Bichon is on it's way out . And it's because you want the Sheltie to yourself. I don't want you to think I'm mean Just remember animals need other animals also.