What motivates our theoretical belief in “the unconscious” to begin with? Quite simply, the incoherence of (ordinary) conscious beliefs. It’s because ordinary conscious beliefs are often contradictory (“I know that my girlfriend isn’t like that, and yet I think she is like that.” – a variant of Moore’s paradox) that we need the category of “the unconscious” to begin with. “The unconscious” is needed to synthesize or perhaps rather isolate a contradiction.
“She did that, because she unconsciously thought that…” is a form of explanation that is meant to save the coherence of the actor’s ordinary web of beliefs – the explanation isolates a (seeming) contradiction.