all good ideas... especially the legos. *SUPERSMIL
in all seriousness... bettas are just lazy fish. they like to find a rock or plant and take a nap on it.
a girlfriend would be a cute idea... but then you should probably get another tank or bowl for the little girl. the boys definitely enjoy the diversion... flaring to show off for her every once in a while, and then giving her that, "hey baby, check out my bubblenest" look.
if you're not ready to do that... make him a pin-up girl...lol. i think sweetvegan is the one who does this... she printed a pic of a female out from the 'net to encourage her little UB to make bubblenests.