First, there is nothing in the image that indicates that either speaker is of a certain gender.
Second, I was pointing out how it can be read as passive aggressive, not trying to say it wasn’t the best course of action. If I comment on someone’s funny video/meme/niche internet microblog, “This was unexpectedly funny!” There are both favorable and unfavorable readings of it. I was trying to be nice, it could still be interpreted validly as the opposite.
Third, I don’t identify with the sender. I have never tried to engage in romantic relationships, and I’m not interested in doing so now. It is hard to identify with someone who is interested in romantic relationships when you aren’t, but I can understand their perspective. If you have ever had a friend who is a straight guy, you can understand how they perceive social ques differently and have different expectations of communication differently than straight women.
However, I agree that this was the best course of action in the situation. Unfortunately, there isn’t a nice way of straight forwardly saying, “Hey, I recognize this romantic advance, but that’s not what I am looking for in this relationship/I am already in a committed romantic relationship.” I think your justification of your argument isn’t valid and seems more like a knee-jerk reaction to me saying something slightly against the grain.