My brother is about 26 yo and has been a serial monogamist since highschool with girls about a 7 or 8. Now he has developed a really bad oneitis for this 23 yo that.s about a 9, which is way over any other girls he's been with. I just cant stand seeing him being stressed out and sad over a girl who is fucking him like 2/3 times a month. He is really good looking and got it okay with girls, but this one really fucked him up and I tried helping him but he just seems to forget everything I tell him the following day. Im pretty desperate since he is my brother and just feel hopeless about not being able to help him. Any solutions besides letting him suffer enough? He is investing like she is his goddamn wife even tho she is just fucking with his mind and using him for self esteem.