Hacker News is supposed to be a community of like minded people sharing their interests with others who enjoy the same thing. I think it is really cute that she did this for her boyfriend. She didn't have to do this, but she either likes him so much, or likes the product so much, that she wanted to help him make it successful.
I don't see how there is anything wrong with that, and if it is on the front page, then others must agree as well.