Butch wanted to settle as far away from the Vault as he could. Rivet City seemed to be the best Butch could get, at least, in the Capital Wasteland. When it came down to it, Butch wanted to leave the Capital. The only thing stopping him, was you.
Your dad lived here, put his heart and soul into the projects with Doctor Li, he died here. Every time it came down to it, you couldn't leave. Butch gave up on asking you to leave since it caused you too much heart ache. So, he found a house near Rivet City and the two of you moved all your stuff into it.
Mementos from your travels, clothes you couldn't bring yourself to throw away, and Butch's things that he had collected. It filled the house pretty nicely and brought together a homely atmosphere.
"Better, doll?" Butch patted your back, watching you carefully as you looked at all your trinkets.