In every relationship, there are some things that you really should not tell your man or woman if you wish for the relationship to last. I agree, all relationships have to be built on trust, however, there is a limit to what you should reveal. See Things your partner should not know about you:
1. Your sexual history: To be frank, not all boyfriends/girlfriends are interested in the narration of your sexual experiences in past relationships. Keep it to yourself.
2. Someone who has a crush on you: You will only be opening the door for issues in your relationship. You will make your partner begin to imagine things.
3. That you snooped through their stuff: Even if after the search, you discovered that your partner is loyal, do not reveal anything. Disclosing it means you never trusted him or her enough.