Other mistake: After Kirsten is talking to Sandy about the fact Seth got into a fight and she comes inside to see that Ryan has made breakfast, there is no way he could of set the table, found all the utensils and ingredients and cooked them by the time Kirsten gets back inside.
Other mistake: In this episode when Marissa and Summer meet Cody Briches on the beach, Marissa says she's never watched "The Valley," which is not true, as in the Valentines Day episode, she's lying on the couch watching T.V and you can hear "Next Time On The Valley."
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.