So when does the next girl get introduced?  Harem is directly in the title.  Now that he has a house, it would be a good time to build one.  Some to bring into the dungeon, and one you leave behind for full time housework.  I don't think you can expect Roxanne to keep up with everything unless you are cutting down dungeon time considerably.  Plus more girls = more girls and that's reason enough for a harem man.
But I suppose he probably needs to go earn money first since he just spent a whole bunch.