Not returned in kind:
— Unrequited (unanswered) love.

synonyms: unanswered, unreciprocated.

Roget 917: ungrateful, unmindful, unthankful; thankless, ingrate, wanting in gratitude, insensible of benefits.    forgotten; unacknowledged, unthanked^†, unrequited, unrewarded; ill-requited.   

Roget 806: indebted; liable, chargeable, answerable for.    in debt, in embarrassed circumstances, in difficulties; incumbered, involved; involved in debt, plunged in debt, deep in debt, over one's head in debt, over head and ears in debt; deeply involved; fast tied up; insolvent etc. (not paying) 808; minus, out of pocket.    unpaid; unrequited, unrewarded; owing, due, in arrear^†, outstanding; past due.    ... show more