lovesick

adjectives

languishing because of love
"strong men behaving like lovesick boys"
lovesick
is derived from
lovesickness
is similar to
experiencing or marked by or causing sadness or sorrow or discontent
"unhappy over her departure"; "unhappy with her raise"; "after the argument they lapsed into an unhappy silence"; "had an unhappy time at school"; "the unhappy (or sad) news"; "he looks so sad"
unhappy