Sometimes i was always in the impression that once a couple were an item there should not be any secret at all between them. But i guess i was wrong. After those years of sharing in everything, finally they stop sharing certain activities and start hiding this and that. Let it be regarding work or latest updates regarding new friend, old friend or old flame.
I came across this in mariage.about.com : Being honest with each other doesn't mean you must share every single thought, dream, fear, or fantasy with your spouse. Honesty may be a double-edge sword in your marriage. Knowing what to share and what not to share is an important communication skill for couples to learn and use in their marriage. If you are keeping a secret because you don't want to face a responsibility in your marriage, this can create problems. Withholding facts or information your spouse needs to know in decision making is harmful manipulation.
Other secrets that can hurt your marriage are ones concerning job problems, not revealing an illness, seeing family and friends secretly, lying about how you spend money, and having an affair. Honesty and trust are vital to the success of a marriage. It's a thin line between what secrets are acceptable and which ones will haunt an individual and hurt a marriage.