A new type of relationship

So it goes like this. I know somebody who recently broke up with her boyfriend. They said they would be friends, but this kind of friendship they "invented" eventually ended up in some things she never thought would happen. They go out a lot, together, with a bunch of friends. They drink, they eat, they laugh, talk & sing, they make fun of stuff, they read magazines and chat nonsense. Whenever they realize that they were together, whenever just a fracture of their past memories come back to their minds , they crack. They crack and do stuff by ignoring anyone else around. They kiss, they hug, they cuddle and act as if they are together and in love. These things obviously raise big question marks in her head. She asked me for help, but I really have no idea what to say. Commitment is something most guys run away from, so d'oh , the guy likes having someone around whenever he wants to give and receive affection. Kissing and kissing led one night to sex. A get-back-together kind of sex? No. A casual one. Just like a one night stand with your best friend. That's obviously wrong, right? I mean, they both have feelings for each other. I know that, believe me, she told me, and he told some of his best friends and some of their common friends. She always thinks they will eventually get back together. She knows he cares for her. The problem is that being codependent, she cracks, whether she's loosie-goosie from a alcohol, whether she listens to the music that reminds her of him, or whether she watches a teenage romantic comedy all by herself, in her room. It's a shame, most guys would cherish her for who she is, but she's just the kind that messes up all the time with the wrong guys. It's sad to be in thins kind of relationship where you just don't know what to do, how to act, what to think and what to expect next. I guess the road to Hell is indeed paved with good intentions [and for those who don't know, that's not a Madonna quote :)))]. I wonder what it's like not having any best friends at all in these situations. I know for sure I'd go crazy if i were in my friend's skin. And I bet it hurts like hell, even though she's still in denial and says it's over for her. Nope, the eyes are the mirror of the soul, so thank God I can read her within a look. Best friends listen to what you don't say ..:)