Sindarin for heart-bonded?

the phrase Heart-bonded, as in bound by the heart in love.

hûn i 'waedh ?

Your phrase hûn i-'waedh means "the heart of the bonds", which isn't what you intend. Perhaps a compound of hûn + gwennen (passive participle of gwedh- "bind") would work, producing hunwennen.

Awesome! Thanks!