lose one's hear to

Fall in love with, as in I totally lost my heart to the new puppy. This expression uses heart in the sense of “the seat of love or affection.” [First half of 1600s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.