The iPhone app connects to the database you specify in the app as long as DVDP is running on your PC. If the databases on your version of DVDP and your boyfriend's version of DVDP have different names, I think it should be possible.
For your purposes you would need to switch the database on the app between yours and your boyfriend's. I would suggest you try this out with the free version of DVDP first. If it works and the switching isn't too much of a hassle you can buy him the license later.