Halloween

Why has every girl I've ever dated been really into Halloween, and in particular, Halloween costumes?  Wont be an issue this year since I don't know anyone in the entire state, much less anyone with romantic intentions toward me but still.  Doesn't that seem odd?  Also, why do I only date girls who got or were working on majors in the humanities and liberal arts department?  The closest I've come to getting out of that is nursing but that still seems to be the same deal.  As an engineer do I just subconsciously feel a need for balance or something?