In no particular order:
Jellicoe Road by Melina Marchetta - it's a contentious sort of swoon, but still swoony
Anna and the French Kiss by Stephanie Perkins - so many cute little things
Fangirl by Rainbow Rowell - basically every part with Levi was swoony
The Crown of Embers & The Bitter Kingdom by Rae Carson - Hector! Enough said.
Catching Fire by Suzanne Collins - the beach!
The Dream Thieves by Maggie Stiefvater - I know, this is not a kissing book. But, that drive up in the mountains!
Scarlet by Marissa Meyer - somehow it manages to be mysterious and swoony
Edenbrooke by Julianne Donaldson - the banter!
The Scorpio Races by Maggie Stiefvater - somehow killer horses manages to bring out the swoon in Sean Kendrick.
The Sky is Everywhere by Jandy Nelson - Joe goes from zero to swoon pretty quickly.
Extra: Under the Never Sky by Veronica Rossi - Perry and Aria are so great together