Been there, got the tshirt.
I'm Single and loving it.
But if you must be responsible, look for a used midrange 500cc-700cc Yamaha or Suzuki. If you treat them right, proper maint. and not hotrodding it, should get you through several years of cheap reliable transportation. Then dump the girl, buy the Harley, and RIDE. Hell, with a Harley, theres always another girl, but never another love.
Homebrew