People may scoff but The Bridges of Madison county is about this, albeit with an older main character(s)

If you’re looking for classics Stendhal’s “On Love”. He was credited for being one of the first authors to accurately portray the mechanics of feelings of love/falling in love.

Spare

I thought Everything I have is Yours by Eleanor Henderson had moments like this. Overall it's a more complicated story of love/ family/ career sacrifice, but the descriptions of falling in love with her husband are giddy and light.