Exactly. The situation described is awkward as hell, even though it might have been accidentally so. Wine is a romantic drink, why not pick something else? Without other people around, it’s an intimate event, doesn’t feel like a work celebration at all. I mean, there are plenty of reasons why this would raise red flags; in most other cases, this would have been a seduction. By doing this, he crossed the boundaries of what’s socially acceptable. Accidentally, he says, but he did. And he doesn’t deny this.

That’s why his reply is so good. He admits he did wrong, and allows himself place to explain his point of view. If he had tried to justify it, or belittle her feelings, it would have not been so effective. He was socially awkward. He failed to read social cues. That’s why he said that if he had known he did this when it happened, he would have stopped. If he had not admitted his part of the fault, the explanation would have not felt so sincere.