Like dating, mentoring relationships don't always work out.
Sometimes the chemistry just isn't there; the two folks involved just don't "get" each other. Perhaps one party doesn't respect the other. Maybe things never get past that "awkward" phase. Maybe neither can agree on a definition of "success" or what actions are required to get there. Maybe someone is just looking to show up while the other expects a big effort.
You can learn something from a bad relationship and/or you can "break up" and find one that does work. We're human. This isn't a mechanical process. It requires trust and vulnerability.
Besides, you never know when something you said /offered /did will come around. Sometimes folks just aren't ready to hear what you have to say but will find it valuable months later.
Be true to yourself. Be ready to do some work (on either side of the relationship). Be prepared to date a little until the right fit comes around.