When you are on rebound, you see the physical image of your ex in other person. Let's say, your ex boyfriend or girlfriend was very tall. Next time, when you meet a tall person, you will be reminded of your ex and you will become emotionally attached to this person because of his physical appearance without knowing his innate qualities. Later on when your heart is healed, you will find yourself that you are with wrong person.
You tend to compare any person with your ex and find that he/she isn't better than your ex. That isn't good either.
If you remember your past love story with sadness instead of happiness, then you are on rebound and not in position to fall in love because you are on rebound. When you fall in love with a person when you are on rebound, you aren't being fair to yourself and to that new person.
However, you can heal your heart and move on. Love is the greatest gift you can give yourself and to the world.When you are in pain, your friends and family can feel the burden. They will be in pain.
So heal your heart and move on. I heard that it takes six months to heal your heart.I wish you all the best.