What REALLY makes men and women fancy each other?

His muscles and his pheromones make my womanhood go in overdrive :P

Pheromones ( hormones that give us a male or female body smell ) , sexual dymphorphic characteristics like muscles for men, boobs for women, make men attracted to women and women to men.

Very few people's brains are 100% straight. The vast majority of people have brains that lean more towards one certain gender but can also feel attraction of some sorts to another sex.

Chemistry

ttraction is a symphony in which many different instruments—wit, voice, charisma, class, and body language—play a part., Psychology Today

Tequila.

If you can enjoy one another's company for copious amounts of time and in between that sometimes engaging in some physical play.