First off, I don't think he was using you. I think he at least feels close to you as a friend, and you were there for him. Second, feelings for an ex can remain for quite some time. In some cases, it never goes away completely. That doesn't mean he won't be open to a relationship with you in the future. It just means that he'll always care for her no matter who he ends up with. Now guys, I am not trying to stereotype, but one fact cannot be denied. It's easier to have relationships with women. You don't have to worry about what others might think. This is something to consider with bisexuals in particular. There's also the whole concept of reproduction. That's not to say, that given the right man, a bi man won't spend his life with another man. It just means that there's a built-in greater likelihood of ending up with a woman. Another consideration is that there are more straight women out there, and that means easier access. It just means that you have to be aware, but also it means that you shouldn't rule it out either.