"We're head over heels!"

ITSLOVE

This phrase completes the classic Elvis Presley song title about deep affection.

The phrase "We're head over heels!" is a common idiom meaning someone is deeply in love. "Head over heels" directly hints at the word "love," and the exclamation suggests excitement or passion. The answer "ITSLOVE" plays on this by combining the possessive "it's" with "love," making it a straightforward but clever fit for the clue.