He was being so contradictory and she wasn't even sure Eros knew he was doing it. Or, if he did, if he cared. First he said that not everyone should choose who to love on their own because they might make bad decisions, which Harmonia couldn't help but interpret to mean that those bad decisions were just decisions that didn't align with whatever he happened to want at that moment. Or perhaps with what their mother wanted.
Then when she called him on that by stating she wasn't going to have any of this arrow or forced loved business, even if it meant waiting for eternity, Eros rudely questioned her over it. As if she was just making a point and would come crawling to him and change her mind one day because pitiful little her really believed that was how things worked. Poor, stupid, Harmonia.
Now he was back-tracking, trying to say that she was rare and special and beautiful and would get what she wanted...without him ever having to stick an arrow in anyone.
Because she was stubborn. Oh, and that part about her also having that advantage of being his sister. Harmonia didn't miss how he said that. The arrogance. She would be one of those rare people... not just because she was his sister, though it definitely did help.
He was back-tracking now, asking her not to leave angry. Probably afraid she'd run off to Ares and he'd get strung up and whooped for it. This wasn't really something their father was going to be of comfort for, though. Eros should know that. “I'm not mad, Eros,” she replied, though there was a firm frown on her face and her arms were crossed over her chest. “I'm just... very disappointed.”