[Great, she's probably an older teen, then. Not much room to talk Eridan out of this. Fortunately, he doubts the girl actually feels the way Eridan thinks she does.]
Because for humans, pity isn't necessarily romantic. [Here he goes, explaining things he never thought he'd have to explain before. He's very careful with choosing his words.] Pity can lead to relationships, but there's no guarantee of it.
Remember how I told you that humans don't have quadrants? We only have "love," which is driven by empathy and a desire to see the other person safe and happy.