I recommend that “open communication” is not necessarily the same as totally honest communication – which I call “the overwhelming truth”.
Open communication involves deliberately telling your partner how you feel, what you want and what you don’t want, but only in a positive and constructive way.
Overwhelming truth means that you may be hurtful or down right stupid in giving “too much information.”
For instance, don’t spill the beans about the time you had a threesome with strangers. This kind of admission can backlash on you for the rest of relationship (which could actually be very short once you’ve told the total truth).
The overwhelming truth may back-fire because it hurts the other person’s feelings unnecessarily. In other words don’t be tactless and don’t leave yourself open to emotional blackmail because you have shared too much.

Resist your urges to find out everything and resist your partner’s manipulation to get it all out of you. Keep the mystery up but don’t give yourself away. Give vague answers if your partner really pushes for a response. Then reassure your partner that you love her/him.

Here’s some helpful answers to probing questions about your past:

Question: How many lovers have you had in the past?
Answer: I was curious to have a range of experiences when I was younger, but now I’m very happy with our love-making and you.

Question: Tell me your wildest fantasy?
Answer: I used to fantasize a lot about different women, but now
I seem to always find you on my mind and my fantasies are about you.

Question: Did you ever have an affair?
Answer: When I was younger, I flirted and fooled around a bit with some women at various work dinners, but I decided that that could get a bit messy. Anyway, who needs to think of anyone else now I’m with you!

CAUTION: There are two things you absolutely should tell all the truth about.
1. Your safe-sex status:have you had any sexually transmitted diseases, have you had unsafe sex with anyone?
2. Your pregnancy risk status: are you on the pill, have you had a vasectomy or a tubal ligation?

Author's Bio: 

Dr. Janet Hall is a psychologist, hypnotherapist, sex therapist, author, professional speaker, trainer, and media consultant. Jan consults regularly with print media and is a frequent guest on talk-back radio and current affairs shows.

Jan was a regular for two years on the Sex Life television program in Australia. Her user-friendly strategies offer practical solutions to sexual and relationship issues so that you can have the love and the sensational sex that you deserve. Jan has a unique ability to encourage people to clarify their situation and solve their own problems with both heart (trusting intuition and feelings) and head (with logical analysis and rational prioritization). She believes that people deserve to feel empowered and allow themselves to be the best they can for the good of all. Jan has a happy knack of making psychology user friendly.

Dr Janet Hall