Expression or idiom: disappointment
Solution 1:
“No good deed goes unpunished”
(No clear origin for this phrase at Wikipedia)
Solution 2:
It sounds like you're feeling unappreciated:
not fully understood, recognized, or valued.
"she had been brought up in a family where she felt unappreciated and undervalued"
synonyms: unacknowledged, unthanked, uncredited, unrecognized, taken for granted, overlooked; undervalued, underpaid