It has been a long assed time. I don't remember what happened in this episode except Seth kisses Alex and I assume we're all pissed.
Episode description from TV Guide:
"It's a romance roulette as Seth and Ryan hit a Killers show with Lindsay and Alex, who'd rather be with the other's escort, while Coop and Summer try to keep their new guys from dumping them for not being over their old ones. Back at home, Julie ropes Kirsten into hosting a party for their skittish clients; and Caleb clues in Sandy to just how bad the DA's case against him may be."