Most Helpful Girl
A first lost love is by far the hardest experience to go through, however even if he says that now, it's not always true that he will forever be single. He could just be taking a break for a while and focusing on other things.
Everyone handles breakups in different ways, each person has a different way to recover, way to heal, etc. It took me nearly 3 years myself to get over my first lost love. I think your brother may need a little boost of self esteem to get over his past, and begin to go out there dating again.
No matter how the relationship ended, the thing he must accept is it's over with and there is no changing it. Once he comes to face the reality that he cannot let that one event effect his entire love life, I'm sure he will begin venturing out to date again. Give him some more time. He will meet a girl one day that he will feel those sparks with again, and she will make him thankful that the old relationship didn't work out. :)
Have faith, and give him time. If you're really concerned about him, try talking with him and get him out enjoying life. Even meeting some other girls (can only be in a friend way of course) but he has to get himself over the loss before he can move on. That's the most important for him to do.