Then maybe you're misreading the look on his face.

[Karkat lets himself be lead. Because right now he has no reason to think anything underhanded was going on. Not only that, Cronus hits on people far more better looking than him, so Karkat's assuming he's just being annoying on purpose.]

What makes you think I even want to know you. One Ampora on my pain in the arse list is really too many Ampora's as it is. So no, no digging.

[To be fair, Karkat did like Eridan. When he wasn't being too over dramatic at least. But as his friend, Karkat had every right to complain about him.]