To fall in love is easy even to remain in it is not difficult our human loneliness is cause enough. But it is a hard quest worth making to find a comrade through whose steady presence one becomes steadily the person one desires to be.
At the end of the day you know love does not happen between two perfect...
But honestly if you do a rigorous survey of my work I'll bet you'll find that biology is a theme far more often than physical science.