Ephemeral:
(adjective)
~lasting for a very short time
A split second decision. A collision. A past that refuses to remain unknown.
This summer's surprise comes with a nasty bite from reality...
ser·en·dip·i·ty
serənˈdipədē/ -noun
the occurrence of an event that comes out to be a benefit or happy surprise
A girl who didn't believe in love and a boy who seemed always hopelessly lost in it becoming partners for a make-it-or-break-it photography project might have been a better instance than they thought.