I'd have to go with "I Will." Even my teen daughters swoon to it.
"It's only love" is romantic too Snoopy
Oh yeah! The idea of being predestined to love someone is very swoonable. But the other songs mentioned, with one exception (LOL!) are good choices too.
An early take...The Beatles - "It's Only Love"
"Here, There, and Everywhere" - also "I Will".