BF/GF vs. Husband/Wife

I feel as though a lot of my peers, both male and female, do not understand the difference between "boyfriend and girlfriend" and "husband and wife".  I am no relationship expert, but my boyfriend and I have been together for about a year, and I found that, the more serious you get with someone, the harder it is to define the boundaries of what is a boyfriend, and what is a girlfriend.  What are our roles in each other's lives?  How much say do we really have when it comes to the actions of our significant others?  I found myself questioning this more often, as the relationship got more serious.

When you first start dating someone, whether you've been friends with this person for a long time, or not, you do experience that "honeymoon" stage.  You're both having fun and enjoying the time you spend together.  This is the part of the relationship where you can't stand to be away from each other and do practically everything together.  You find yourself always laughing, and your arguments aren't even really arguments.  It's silly stuff, like playing rock paper scissors to see if your movie night will consist of a chick flick, or an action movie.  However, as the honeymoon stage fades away, and your arguments become a little more heated, this is when boundaries began to get tested.  

I'm 22, I have no kids, and my main focuses are my education, my family, and living life.  A significant other is just the cherry on top.  I love the cherry on top, that finishes off the ice cream.  Like the cherry, a boyfriend/ or girlfriend is just that added goodness to everything else you have going on.  Sweet and simple, but can bring so much happiness.  I honestly feel like if there is no marriage, the complications of the relationship you're in should be minimal.  I mean, neither of you really share anything significant (i.e.-bank accounts, a house, a car).  The only thing shared between a boyfriend and girlfriend are trust, communication, and loyalty.  If any of these things are broken amongst any party, the opposite person has the choice to LEAVE.  You're not bound by a marriage.  You're not obligated to work things out.  Of course, if you feel like you are in love, and that this person is the person you're meant to be with, then you should definitely do all you can to make things right.  However, if there are constant arguments and disagreements, you have the CHOICE to move on.  Why be unhappy if you don't have to be?  Why complain and mope about the situation when you don't have to?  Ultimately, what I'm saying is, boyfriends and girlfriends only have to tolerate so much from one another because they aren't husband and wife.