痴情人儿多寂寥
[chī qíng rén ér duō jì liáo]
It translates to 'lovers deeply infatuated tend to be solitary' or 'people who are obsessively in love tend to suffer from loneliness.' It expresses sorrow about people who pour all their attention into love often find themselves isolated from others or moments, due to single-minded devotion.