The secretions of chemicals that are associated with two people in love are caused by a complex interplay of hormones, pheromones, and other biological factors that are not entirely understood. https://www.byquanna.com/blogs/qurious-club/increase-sexual-chemistry (I love it a mystery still)
I can feel the excitement in the presence of a woman whom I am attracted to. It can start with a distant glance and if we get closer my heart beats faster and my breathing gets deeper. If we talk I have to be careful to keep my composure and not fumble with my words or if I bring her a cup of coffee shake spill it. Heighten my guard so I don't act foolish. If we brush against each other it freezes me for a second. If we kiss even a simple hello kiss is like an electric shock. Even looking into her eyes at the right moment can jar my whole body.
Love at first sight? I don't know. Lust? I don't know. Yes, that thing we call chemistry that even science can not fully explain. I love it.