Definition: make someone feel annoyed, upset, or disappointed.
Without the right non-manual signals (e.g. mouthing), it wouldn't be the same meaning.
Gloss: REALLY IX1 CAN HELP BUT IX1 DID-NOT; IX-me DISAPPOINTED(oo).
English equivalent: It really bummed me out that she could have helped and didn't.
The modal verb such as "could" in ASL is signed as TRUE+CAN. This gloss "TRUE/REAL" is not literally "true" nor "really" but there is no right gloss for it.