It's the good ol' "I'm charging up from a hug with my lover" thing in romances, except he's a bit of a coward for some bonafide body-to-body contact like how it's usually played and does it with her hair instead.
Calm down with the flag baiting, both of you. Should've just gotten her a ring instead of a necklace; that could've been finished much earlier, he'd have confessed already and they'd be here on the battlefield as officially lovers instead of unofficial mutual crushes.
Well, it's the power of love's time to shine...