Because by wanting to want him, she is betraying her daughter and her own principles - at least, the principles she used to believe in. The basic principles that most people probably believe in, that it's wrong to desert one's child, it's wrong to go through life taking and never giving, trying to mess up someone else's relationship, never thinking about anyone but himself, never caring about what he does to other people, especially his own daughter.

The Lorelai we knew might have hoped he would grow up, would mature, but she never condoned that behavior or shrugged it off. Not until this year.

Being plain stupid isn't the same as betrayal.

It was worse than non-sensical. Running off with a guy she met in a bar would be non-sensical. And we wouldn't need to try so hard, because it wouldn't betray - yes, that word again - who she was.