wear one's heart on one's sleeve

wear one's heart on one's sleeve ( show one's feelings openly) — не (уметь) скрывать своих чувств; не отличаться сдержанностью; быть быть очень открытым; с душой нараспашку;≈ что на уме, то и на языке (контекст.); ≈ рубаха-парень

She is wearing her heart on her sleeve and everyone knows that she is having problems with her boyfriend again.— Она ж ничего в себе держать не может — душа нараспашку: все знают, что у нее с парнем снова проблемы.

From the old custom in which a young man tied to his sleeve a favour — perhaps a ribbon or handkerchief — given to him by a lady as a sign of her affection (i.e. of her heart). The expression is now used of one's own heart (i.e. feelings) on one's own sleeve.