I had to think about this. As a heterosexual, I want to say chemistry.

(Others have brought to non binary individuals but I have to confess that I can’t make assumptions about their dynamics.)

Sometimes I feel the same way with problem solving as I do when I am attracted to a person. It makes me wonder if competition and inter personal romantic chemistry are related wrt how our brain perceives it.

And there is limited/fixed mental bandwidth that we can only focus on one at a time? Just wool gathering..off the top of my head. What do you think?