There are just somethings that you want to avoid in your relationship and lying is one. No matter what is going on you should feel confident in your self and your relationship that you can tell your partner anything. Relationships are based off of trust, communication and understanding (see http://relationships216.blogspot.com/2011/04/how-to-make-your-relationship-work.html). If you lack these qualities then the best thing to do is let your partner know and try to move on.
Secrets can cause a person to tell lies and you just cant tell one lie you have to keep up with what you have already told so you follow that with another lie. That to me is sad if you can't be real with the person you love then you can not be trusted. Trust is major in any relationship, and once you loose your trust then the relationship can go south. How does a person over come someone who keeps so many secrets? Is it possible to move on from the hurt you have experienced behind the secrets?
My answer to those questions are: you can move on from the secret but you will never forget and in the back of your mind lies thoughts of what else is this person keeping from me. Well if your relationship is based off of faith pray about it. Then the best thing to do is sit down talk with each other and clear the air. It helps to be comfortable clearing the air and receiving the information as well. This shows maturity in you and your partner and the respect you have for your relationship.
The key to this message today is honesty, without this in your relationship you can not go far. Keep an open mind if you are the person keeping the secrets think about how you would feel is the shoe was on the other foot. Be real be truthful and be honest, you will be respected more if you are.