Some things ought to be kept sacred. What happens behind closed doors should stay there. I'm not only talking about "what happens in the bedroom," although that's definitely up there on the list.
If you treat something as sacred, you make it special. It's private, and it's important. You don't tell the whole world, or facebook, or even your mother. Your relationship with your spouse is very special, and won't last if neither of you feel that you can trust each other or that you don't have the privacy you need. It will not help your relationship if you go to your friends or parents or siblings with stories about sex, disagreements, or insecurities. All it will do is damage your spouse in that person's eyes and hurt your spouse's trust and ability to be honest and vulnerable with you.
Talk things over with your spouse. If you are upset and need to vent, (it's ok, it happens sometimes) prayer and journaling are both great ways to get your emotions out and think through how you really feel without saying things that you don't mean to your spouse or saying things that are only your business to other people.
This summer I was going through a rough patch emotionally and physically (morning sickness is no picnic) and I got really frustrated with myself as well as being more irritable in general. I asked Cameron to not read my journal (not that he did before, but I just wanted him to know that I needed that to be a private place in case I ever left it out) and put all of my frustrations in there. Sometimes I've used my journal to keep my emotions pent up, but this summer I used it to let off steam. I said things in there that I didn't really mean, or would have sounded wrong if I said them out loud. I needed somewhere to gather my thoughts before I went to Cameron with problems or for help so that I didn't say something hurtful.
Before we were married I would have vented to my mom. She and I have always been close and I used to tell her everything. I've learned now that some things are meant for just Cameron and I, and that's ok. It doesn't mean I love my mom any less or that we're not as close. I can still talk to her about wishing we had a dishwasher or pregnancy questions or anything that isn't private and between my husband and I.
Don't post your feelings about relationship problems on facebook, twitter, or other social media and public places. It's not good for your relationship and it's awkward for others. If it's a cry for help and you want your spouse to see it and fix whatever problem, this isn't the place or the way to do it. Instead, talk to them in person. If you really are too upset to talk, consider writing a letter or email, carefully going over it to make sure that you're not being hurtful, only honest, and asking your spouse to read it.
Keeping these things out of public eyes doesn't mean you're lying. You don't need to pretend to anyone that you have a perfect marriage. It's ok to admit to faults and problems. However, sharing details of your personal life with your spouse is not something that should be done without careful consideration and consent. It's his (or her) relationship as well, not just yours.
Happy things can be sacred, too. There are times when I just want to tell the whole world how wonderful my husband is because he did x, y, and z for me! I have trouble holding it in, but sometimes there are things that should stay just between us, even if they are wonderful and make me incredibly happy. I try not to post the contents of the love notes he leaves me, or sometimes the gifts or acts of service he does for me. Because I love and appreciate them so much, they are very special and something that ought to be just between the two of us.
There are rare occasions when this rule needs to be thrown out the window. If you feel that you are in an abusive relationship and you have tried to communicate this to your spouse and nothing has changed, seek help. Don't try to hide or be strong. It's not selfish to protect yourself from physical or emotional harm. Do it in the proper way (again, not in your facebook status) but do something about it. You never have to be stuck somewhere where you do not feel safe. It doesn't have to mean divorce. I know people who have mended a relationship that was on the verge of falling apart and are now blissfully married, but I know others where it was good and necessary for the couple to separate. Consult the Lord as to how to deal with your specific situation. He loves you and he will not lead you astray.
Don't forget to tell your spouse how much you love them today!