How do i help my friend get over my brother?

Ok so I have this friend ive known since the frist day of pre-school. We always hung out and she knew my family well even my older brother, younger sisters and younger brother. She moved away in 5th grade and just recently moved back, im like her only friend here so we hang out alot and i love her to death (so happy to have her back in my life). Were in our 20’s now so we’ve all done some growing up. Well one night we were at my house having a few glasses of wine when she said “wow your lil brother really grew up” (hes 19 almost 20 now) I said “yha he has, hes quit the looker lol” well she asked if i minded the fact that she liked him and I said ” no not at all have at him hes single just dont hurt him”(honestly it really didnt bother me). Well they started talkin and she really started to like him. One night we were all drinkin at the house and they “hooked up” if you know what i mean. After that she told me that he started acting like he barely knew her. At first she thought that it was he was embarressed about the sex because he was drunk and kinda “sloppy” but about week later she had enough and confronted him by asking if thats why he changed his attitude toward her, she said he said no and stoped responding to her msg’s. Now I dont get involed in my brother personal life because frankly I dont wanna know and I think if I tried talking to him he’d wouldnt be honest with me because he would think id tell her. Its been almost 2 months now and she says shes over it and never talks about him except when she comes to the house she always askes if hes home first, what hes been up to and if hes not home where is he and when do I think he will be. And once in a great while shell ask me why I think he did what he did and acted the way he did. I have never known my brother to be like that either, hes always been respectful and honest when it come to girls…but anyways I really dont think shes over him, what can I do to help her either get over him, give her closer or something…