Not all divorces end on a completely negative note. In fact, some exes do just fine as friends, making divorce a little easier for the adults and any children who are involved. If you begin a new relationship, your friendship with your ex-wife may initially be awkward as everyone finds their places in your respective, overlapping worlds. Being respectful, diplomatic and patient can help you, your ex-wife and your new girlfriend settle into a comfortable set of interactions.
Be transparent with your new girlfriend and with your ex-wife. Keeping secrets, even ones you don't believe are harmful, can be interpreted as you being less than truthful. If you plan on spending time with your ex-wife, be honest with your girlfriend about where you will be and who you will be with. Avoid using friends to "cover" for you by creating a fantasy trail of where you've been and with whom you have been spending time. Respect your new girlfriend's feelings about your friendship with your ex-wife. You shouldn't have to completely change your behavior or disavow your friendship, but you also may not realize that some things you do may be crossing the lines of friendship.
Identify and enforce clearly defined boundaries for your friendship with your ex-wife. Healthy boundaries help relieve both you and your new girlfriend from bad behavior, fear and emotional pain. Clearly defining the nature of your relationship with your ex-wife by stating, "We share an interest in photography and are members of a local hobbyist group," can let your new girlfriend know the parameters of your continued friendship. Establishing boundaries also allows you to avoid defending your friendship with your ex-wife.
Communicate with your ex-wife regularly, but keep out personal details that don't pertain to her. You're in a unique place, with an ex-wife who is also a friend and a new girlfriend who is likely turning a critical eye on your friendship. Since you and your ex-wife are no longer married, detaching from the details shared by married couples redefines your relationship. Begin to approach your ex-wife as you would any friend and be aware of your tendencies to unconsciously fall back into your more intimate manner of communication. Practice being more of a friend than an ex-husband as often as possible to create a new dynamic between you.
Suggest that your ex-wife and new girlfriend join you at social events. It's unrealistic to expect your new girlfriend to be immediately accepting of the prospect of your ex-wife remaining in the picture. Incorporating your ex-wife and new girlfriend into your life in a social way can be less intimidating for both of them and for you. Avoid circumstances where your ex-wife and new girlfriend are forced to be near or sit next to each other. If they do so, by choice, it's a sign that your effort to calm ruffled feathers may be working, but don't force the issue.