Question: fun things to do with your boyfriend that's cheap?
Answer: Play in the snow, build a snow man, then drink cocoa.
Go to a community play, a dress rehearsal, high school or college play.
Do an inside or outside picnic.
Work out together. ... 
Go roller skating or ice-skating.
Movie marathon with ice cream sundaes. ... 
Play hide and seek in a corn field (or the woods)