The psychology of the Average Joe keeps me coming back for more.
Brian has the emotional connection going for him at this point. Larissa knows that she can trust him, and that he will always be devoted to her. I'm not sure it's enough, though.
Plus, if I were writing the show, the Average Joe needs to win the second season, to make up for the first one, especially since they showed Larissa being so shallow at the beginning of the show.
BUT, I still find it hard to believe that a girl like that would pick a guy like Brian, even as much as I can relate to him. If it does happen, I can see their relationship not working out. After which, Brian will not date for 5 years or something.