Many people have an even harder time moving on after a breakup because their ex has met someone else. If you feel like saying, "help, my ex girlfriend has a new boyfriend", take heart, there may be some things you can do that might help.
The first thing you should remember is that just because your ex is dating someone else, it doesn't mean that it's anything serious or that she is actually in love with him. It may just be a case of her finding someone to help her feel a little better about the breakup too.
The truth is that if you handle the situation the right way, you can still get her back. The last thing you want to do is to make nasty comments about the guy she is dating. If you do that it will only make you sound childish and jealous. That will either annoy her or have her think of you as someone who is still in love with her.
Be polite and keep the lines of communication open. If she is still calling you to talk about her new guy it means she still wants you in her life and she trusts your opinion.
If you take things slowly and are receptive to her calling you (without being too accessible, you don't want her to take you for granted either) than after a period of time she may realize that she still has feelings for you.
When someone loves another they don't just get over it. The feelings can smolder for weeks, months and even years. If you want your ex back your best bet is to stay close and be a good friend. Let her remember all the love she once had for you and allow that ember to ignite into a flame once again.
If you are asking, "my ex girlfriend has a new boyfriend what can I do?" don't worry. It is still possible to get her back.