IHMO,
The best way to forget someone or fill up the void he/she left
behind..is to find another one. Try to be optimistic. Think about
it. Perhaps you really like that "rebound" guy/girl, and in time
will love her.
Think about this situation. You have just fallen out of love, and
there's this girl who has always been there for you. She likes you,
is sad when you are sad, happy when you are happy. All the while
she has been listening to you whine about ur ex gf. Suddenly, you
realise that she's the best thing that ever happened to you, after
your ex gf.
Do you consider this girl as a "rebound" ??
In the situation ruth has mentioned, its about you being the
rebound guy/girl. Have anyone of you ever thought of, what if you
are afraid that this girl/guy might be a "rebound" for you, and
afraid of ending up hurting his/her feelings, and eventually,
cheating yourself instead ?