。
She was feeling down.
Literal
She [topic-は] was-depressed [feminine-わ].
落ち込む ('to feel down / become depressed') uses the 込む compound-verb auxiliary, meaning 'to sink/fall deeply into' a state. The sentence-final わ is the feminine assertive particle — adds a softer, more feminine-marked assertiveness to the statement. Traditionally marked as feminine speech, though usage has shifted.