Do you think it fits the girlfriend case in the OP?

I do not. I think you are entitled to the truth about your partner's opinion of things that are important to you. Your partner's, note; perhaps also your close friends'; not anyone's.

I mean, do you think you are wronging your partner if, when they press you for an assessment of their performance, you lie to spare their feelings?

I would feel wronged, if I was said partner. I think that if you're in a relationship with a person who values truth, then yes, you are wronging them by withholding it to spare their feelings. If your partner is someone who does not value truth, then, I think, you are not wronging them by lying to spare their feelings. I'm not sure about this. To me, it is a moot point; since I've noted, I would never want to be with such a person.

Are you wronging your partner even if you know you are fulfilling their preferences by lying? (or does that disentitle them to an answer?)

The question of whether they are entitled to the truth is not actually relevant, as they are not asking for the truth in such a situation; they are asking for something else (validation? support? I don't know).