wear one's heart on one's sleeve

wear one's heart on one's sleeve also pin one's heart on one's sleeve  {v. phr.}

To show your feelings openly; show everyone how you feel; not hide your feelings.

She wears her heart on her sleeve. It's easy to see if she is sad or happy.

Sometimes it is better not to pin your heart on your sleeve.

Compare: OPEN ONE'S HEART.