head over heels (in love)

to be in love with someone very much.

It's obvious that they're head over heels in love with each other.

Usage notes: often used with fall to describe the beginning of a relationship:

They met at a nightclub and instantly fell head over heels for one another.

• a tight-arse
• a tin ear
• a tin god
• at issue
• at knee
• at large
• at last
• at least
• at leisure
• at length
• at liberty
• at loggerheads
• at long last
• at loose ends
• at low ebb
• at most
• at mother's knee
• at no time
• at odds
• at odds with
• at odds with someone
• at odds with something
• at once
• at one fell swoop
• at one sitting