Smart women can have bad taste in men, too - nothing unbelievable about that...So she likes losers? I hope they go further as to why she likes him or else I'll just assume she's got bad taste in men.
Yuu's mom was patient zero of a girlfailure virus that managed to jump the gender barrier and now Japanese youth is full of boyfailures....Alternatively, Yuu got his height and clumsiness from his father, and said father really got around.