Larissa seemed to be torn between choosing a guy that she had a great emotional connection but no physical attraction (Brian), and a guy with a strong physical attraction and a slight emotional attraction (Gil/Jim). I believe she wanted a spark to be there between her and Brian. Before her hometown date with him I think she said something like she wanted to see his moves or something like that. So she wanted to have some attraction there, but it just never materialized.
I don't think that Larissa's choice is that unique. It seems to happen all too often. A woman will say she wants a nice guy who will treat her right, but she'll fall for a hunky, good-looking guy. Then when the hunk dumps her, she'll cry on the shoulder of some nice guy that she "just wants to be friends with".
I'm not trying to women-bash with this. But it seems that the pattern in Larissa's behavior is pretty common. Intellectually she wanted to have a relationship with someone where there was a strong emotional connection, but in the end she let her physical desires make the choice. She even 'deluded' herself that there was emotional depth to Gil.
Men follow their physical desires too, but they are usually more up front about it. Ask a man what he wants in a woman and probably the first thing he'll say is that she be attractive.
So I can't blame Larissa too much for the choice she made. I had hoped that the underdog would have won, but it did not happen. I feel Larissa made the same choice that many other women would have made. Or actually, the same choice that many other people would have made.