I do not have it in me to feel remotely sorry for those people who become so involved in their relationships that their friendships take a back seat and you never hear from or see the person until their relationships is over at which point they have lost all the friendships they once had. That seems to be an error many people make and although you may become very involved in a relationship and you will not be able to spend as much time with your friends as you did before you should not put them on the shelf until you need them. Do not blame your friends for moving on either, because friendships also take work and commitment. People carry on with their lives and there is no reason why you should not be able to spend time with both your friends and your new partner. Also, everyone knows that the first couple of months is the honeymoon phase, but that does not mean that you need to climb all over each other in front of your friends and make everyone horribly uncomfortable either. Learn to control yourselves, because it is just the respectful thing to do. No one wants to be made to feel like a third wheel.
Imagine how lonely it must be to come out of a break-up and you have no friends as a support system? Should everyone suddenly rush to you after you have neglected them for months and some times even years just because you are now single and have no one? All I can say is that if you want to forget about everyone until you are single again then I hope you have one heck of a sturdy back bone to see yourself through the emotional ups and downs you have ahead. You cannot let your life become all about someone else and lose yourself along the way because it is a recipe for disaster. You need to keep your other relationships going