Continuity mistake: When Ryan is lighting Marissa's cigarette with his, at the start of the shot it's full, then the shot goes to Ryan and it's still full. But then the shot goes to Marissa and if you look at Ryan's cigarette you can see it is almost all gone. Then the shot goes to Ryan and the cigarette is full again. (00:09:00)
Continuity mistake: When Marissa is dumped on the driveway by Summer and Holly, Ryan first sees her there her left arm is across her chest with her elbow sticking up. The next shot of Marissa her ams are straight and spread out, and the next they are close by her sides, which is impossible for her to have moved them herself as she is unconscious. (00:34:15)
Continuity mistake: When Sandy first picks up Ryan, we see in several shots that Ryan's bike is in the trunk, and that the trunk is open. However, when they drive up to the house, the trunk is now closed, with no bike.
Continuity mistake: When Ryan and Sandy leave to take Ryan back home, it is supposedly the morning. But as they leave, the sun can be seen over Marissa's shoulder, which is the west (because her back is to the ocean). Since the sun sets in the west, it can't be morning.
Answer: He means that if Alex has to go so far as to forbid Ryan from seeing Marissa in order to maintain her relationship with her, their relationship obviously isn't working.