I love puns and this is one that I had never heard before. Enjoy! There is this Internet Marketer for a large company and he has a girlfriend called Lorraine who is very pretty and he likes her a lot. One day he goes to work to find that a new girl has started. Her name is Claire Lee and she is absolutely gorgeous. He is fascinated by her and after a while it becomes obvious that she is interested in him too. But this guy is a loyal man and he wouldn't get involved with Claire Lee while he was still going out with Lorraine. He decides that the only way is to break up with her and start a relationship with the new girl. He plans several times to tell Lorraine but he can't bring himself to do it. One day they go for a walk when Lorraine suddenly tells him that she wants to break up. The guy goes back home alone and starts smiling and singing: "I can see Claire Lee now Lorraine has gone."
You had to be there... Seriously, I did worry a bit about some readers not understanding the pun, but @malky66 has provided the solution.