A person who is newly independent after a break up is often vulnerable to getting into a rebound relationship with a new partner. When a serious relationship ends, it can leave a huge emotional gap that screams to be filled. Because you are still being strongly affected by feelings from the prior relationship, you cannot always judge things as clearly as you should. A rebound relationship is often based on feelings that have not settled from the upset of ending the former relationship. This can lead to rushing into something you will regret later.
Entering into a relationship too quickly after a break up can end up hurting both of the new partners. If you think that you may be on the rebound, you should take a look at what you think of during an average day. If you are still dwelling on the previous relationship and talking about it to friends instead of focusing on your new relationship, this could be a warning sign. Experiencing feelings of anger and hurt after a break up is normal, but if you are still focusing on it when you are alone, you may be on the rebound.
Likewise, if your new partner seems to be distracted by a former relationship, you should consider whether or not they have jumped into a relationship with you too quickly. Look out for warning signs from them just as you would for yourself. If you are concerned, ask them how long it has been since they were in a serious relationship. You can be subtle about this of course. Notice if they are hanging on to items from a past relationship or if they mention their past relationships too often. Talking about your past is normal. Dwelling on it can be an issue and does not help anyone.
If you think that you may be in relationship based on a rebound, you do not have to give up on it entirely. It may work out fine. You should express your concern to your partner in the interest of honesty and consider taking things a little bit slower so that you can both be sure that you are using your best judgment and thinking with clear thoughts. The ending of an old relationship and the beginning of a new relationship are very emotionally charged times. Bringing them too close together without some restraint can cause problems down the line. It is often wise to take things slowly after a break up and get your feet under you before moving forward.