"Uh," Seth considers, leaning back a little. "Well. Gabe came by, said I'd given terrible advice in saying he should tell you how he felt, and that you'd left, because he told you he loved you. That's it, really."

It's kind of tricky to include the 'Gabe implied it's my fault you left', without implying that himself.

They got kind of distracted after that point, and then, well, Seth was dealing with too much of his own shit to inquire further. Or at least to inquire further specifically from Gabe.