be head over heels

be head over heels (in love)

to be in love with someone very much, especially at the beginning of a relationship.

 

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

(head over heels 照字面上的意思是頭朝下摔倒，另一引申義就是completely, uncontrollably完全地，失控地。所以，head over heels in love 就是熱戀中囉！)