I’m no authority on this; I’ve only done with 1 girl 0<(1/2) of what I’m about to describe, but I’m confident in my theory and don’t mind being wrong. The whole idea of foreplay leading up to the climax of penis in vagina speaks to the dominance of males in our society. P in V is generally the most sexually stimulated a man can get, but it is generally not the most stimulating arrangement for a woman. Maximum enjoyment for a woman comes in the form of stimulation of the clitoris, clitoral shaft, and both cruras. The penis is ill-equipped to do this. Fingers can.