Honesty is the best policy. Marriage is a relationship between two people who love and care for each other. Someone you can be yourself around, someone you can make life long decisions with, someone who will except you for who you are and what you do is all within the package. Keeping things from one another is not okay. Keeping secrets, and hiding feelings is basically contradicting your marriage. Why would you marry someone you don't trust? Are your planning on sleeping with one eye open? When you marry, you are making the decision to trust your partner to share the rest of your life with.
If one feels they must hide things from the person they marry, then they obviously should have thought twice about marrying that person. Communication is vital to keeping a relationship healthy and strong. Hidden feelings may become a problem and may become stronger and harder to keep. Keeping things from your spouse is not normal, and it should not be an option when being in such a committed relationship.