When relationships end, one partner might still have lingering feelings for their ex and try to keep in contact with her. This can result in problems with new relationships and create resentment or anger. If your girlfriend's ex-boyfriend won't leave her alone, try to make him to understand his actions are unappreciated and unwanted.
Talk to your girlfriend about the issues she is having with her ex. Ask her to consider telling him to leave her alone if the communication is unwanted. Many times, simply asking someone to leave you alone will be effective.
Speak with your girlfriend about confronting her ex-boyfriend yourself if she does not feel comfortable doing so. Get directly to the point when speaking with him. Avoid being irate or rude but make it clear that you want him to leave her alone.
Sit down with your girlfriend and discuss ways she can cut all ties with her ex-boyfriend. For example, she might consider changing her phone number and email address.
Consider getting a restraining order against the ex boyfriend. If he is making abusive threats or tries to physically harm either of you, contact the police immediately and ask about obtaining a restraining order.
Have your girlfriend ask the court to require her ex to eliminate all contact during the restraining order issuance. Instead of just requiring him to stay away from her physically, this will prevent him from sending her gifts, calling or emailing her.
Speak with your girlfriend regarding custody arrangements if she has children with her ex. Ask her to go through the court system to make the arrangements concrete so that her ex cannot try to negotiate visitation. Have her ask for supervised visitation if you expect any issues to arise during the visitation.