Dating someone who's divorced is very common. There are things you can do for relationship success.
Marriage is the triumph of hope over experience. Samuel Johnson
This is especially true when you're talking about remarriage. In this day and age when just under half of first marriages fail, there is a good chance you may become involved with someone who has divorced. The older you are, the more likely this is to happen.
With second marriages failing at an even higher rate than first ones, there are a few things you should be aware of as you negotiate this relationship.
1. How many times has your partner been married? One unsuccessful marriage is not all that unusual. More than one should raise some red flags and prompt some specific questions. What did your partner think marriage was about? Do they understand the stages of marriage and which stage each marriage was in when it ended? Are they in love with the idea of love versus the reality of building a life with someone else? As Dr. Phil says, "What is the common denominator" in these relationships and does your partner have the ability and desire to be successfully married?
2. What was their part in the marriage not working out? When you're part of a couple, you have a built in scapegoat when difficulties arise. However, relationships reflect what each party brings to the table and how they act and react with each other. Be wary if your partner lays all the blame at their ex's feet. There are rare circumstances when one party truly does bear the burden for the failure. Addiction and abuse are the two that come to mind. In all other cases, your partner should be able to reflect on their contribution to the relationship's demise.
Infidelity is a special case because, while your partner is not responsible for the behavior of their ex and adultery is never a productive choice, their marriage was vulnerable for some reason. I consider serial infidelity, the inablility or unwillingness to be monogamous, to be a form of addiction or abuse. Even so, your partner hopefully has given thought to what they missed while dating their ex or why they stayed once the behavior became obvious.
All life is a learning opportunity. But it's often too easy to walk away from a relationship and leave the unpleasant stuff behind. You don't want to get too involved with someone who isn't able to explain what they learned in their marriage and how they will do it differently with you. The two of you will make your own mistakes, you don't need any preloaded ones.
3. How does your partner speak of/interact with their ex? If your partner uses harsh language or disrespectful tones, it may mean there is unfinished business. If their partner can still get them riled up, they are still emotionally connected to them. This is of major importance if the two of them have children. This person will then be an integral part of your relationship on an ongoing basis.
Even if they have no reason to be in contact, your partner is still sending emotional energy to them. This negative energy can only pollute your relationship. If your partner cannot truly wish their ex well, no matter how much of a pain they are, they are still tied to the old marriage. The opposite of love isn't hate, it's indifference. Too much reaction means your partner isn't really ready to move on with you.
All relationships carry risk. Intimate relationships carry the most because of the trust and vulnerability involved. Going in with your eyes wide open, while not necessarily romantic, is a good strategy for success.
Getting involved with someone who has been married isn't a bad thing. Just remember to proceed with caution. After all, those who don't learn from history are often doomed to repeat it.