I think the response from Kara S is very good. Check out this link about living together http://www.citizenlink.org/FOSI/marriage/A000000982.cfm
The following excerpt is from Dr. James Dobson, Physchologist:
"Studies show that living together before marriage creates problems, while marriage has emotional as well as physical benefits.
Statistics indicate that 40 percent of couples who live together break up before they marry. Research also shows that living together is correlated with a greater likelihood of unhappiness and domestic violence, as well as lower levels of satisfaction in the relationship.
Children are also more likely to be abused by their mother's cohabiting boyfriends than by her husband, even if the boyfriend is their biological father. Additionally, if a cohabiting couple eventually marries, they report lower levels of marital satisfaction and a higher propensity to divorce.
Married couples, on the other hand, live longer, healthier lives, are less prone to alcoholism, enjoy greater emotional support and have the highest levels of sexual pleasure and fulfillment. "
One of the reasons this is, is because before people cohabitate, they only think about how they are getting along at present. Then they get surprised when they don't get along living togther. Then they are trapped in a relationship which they didn't realize is every bit as serious as marriage. So it's harder to back out than they thought. When people marry, they think more reastically about the relationship they are entering into and are less prone to making a rash decision, because there is all that planning to do! Then, because of this, they have made a better decision.
The other thing to think about it your daughter and YOU need a partner for you that's permanent. Going in and out of relationships would deteriorate the respect of her towards you eventually, even if it's not your fault he left. I've seen cases where the boyfriend left and the child because angry, withdrawn and had all of the same problems that it would have had if the couple were married. Marriage gives the stamp on that permanence. Makes a better chance for it to happen. It is a "contract" that says to you, your partner "we are going to commit to being together for the rest of our lives". If you can't make that commitment with a child, it's best not to cohabitate. This is very important especially where children are concerned. In the event if your partner leaves, it's going to feel exactly like a divorce whether or not you have officially got the "papers" of marriage.
So, may as well have the legal contract. Plus it gives a message to your daughter that this is more than just a live-in situation. It gives your daughter the message that our lives are not to be lived so lightly - that we need to make commitments. So it's mentally healthier for your daughter as well and will help HER make better decisions and not give herself to men lightly when SHE gets older. You want her, when she gets to be old enough to marry to not flit in and out of relationships. This is very harmful to a woman's self-esteem and soul.
You didn't mention why you want to live with a "mate" without being married. It's harmful to the family unit -it's the woman that loses in most cohabitation, because we are more emotional and committed in our relationships, especially if we have a physical relationship than the man. No marriage contract means to him he can leave whenever he wants. Then the woman ends up living in poverty with her children "holding the bag" so to speak.
God is merciful and LOVES mankind. You are made in the image of God. That's the main thing you need to know about ORTHODOX Christianity. No one in Orthodox Christianity would EVER tell ANYONE they are going to hell. We rely on the love of God for everything. I've done worse things than cohabitate with someone in the past, and would never tell anyone they're going to hell. Thank God we have confession so I can get rid of old bad stuff. Please don't judge Christianity on a few crazy people with bigger mouths than brains. God knows us well, knows us better than we know ourselves and loves us anyway.