Allow me to be very blunt about this...
If you have an idea that you're on your way to a happy marriage and your partner thinks the whole relationship is just a fun "fling"... then you're obviously traveling down a path of imminent problems. The devastation, pain, hurt emotions, misery, and broken hearts all tend to lie in the immediate future of ALL couples that fail to define what sort of relationship they're in.
You see... the problem lies with our own impressions and thoughts. Everyone assumes things are normal and tends to think of their actions as normal. The problem with that is because there is no such as normal. We area all uniquely different from the next and have our own unique set of needs, desires, turn-ons, fears, and personalities. The strong points and weak points that makes us up is what defines who we are... much like it can define our relationships and what is needed from one.
Whether we realize it or not, we are all using ourselves as the baseline for "normal" behavior.What this means is that on some very basic levels, we are going to assume that other people want what we want, feel what we feel, and desire what we desire. Most of us are aware on a conscious level that this isn't the reality of it all, but it's hard to put it into perspective at a conscious thought process at every given moment in time.
As long as things seem to be going okay, we have a very natural tendency to let this continue more and more. Because what can seem more normal then that? They're happy... you're happy... everyone's happy! So there's no need to examine our expectations and assumptions about our relationships until things go wrong.
This why the need to define the relationship early on is so beneficial, because everyone else is....everyone else. They may be happy in the relationship, but they could be happy for different reasons then you assume or think. If you let this go for to long, then you're only going to be setting yourself up for disappointment and pain. Even a heap full of resentment and depression.
When you honestly take the time to define the relationship, you are taking hold of the reins in your relationship. You can see where you are, where you wish to be, what path you desire, and where you are going to be heading. This will allow you to have a healthier, stronger, more deeper relationship because you will both be pulling in the same directions rather than a pushing effect as I have often given advice about on many occasions and the effects that pushing will have on destroying your love for each other.
The uncomfortable issue that arises with defining your relationships is the problem that it's not the most easiest of tasks to do. It can be quite uncomfortable and awkward, even nerve racking to discuss. And there is always the fear element that your partner will reject you or have a much different opinion. Their desires, expectations, and goals might not be the same as yours and you only learn that your relationship is coming to an end much sooner then you would have ever been able to foresee.
While this fear is valid, it is for the best that you define your relationships at an early stage because it is actually for the best. You'll have to look at the efforts involved with trying to define the relationship as being an exercise of love and respect for your partner. It can be pretty tough sometimes, but at the same moment there is a small chance you might get hurt. And in the end of it all, the truth lies in the fact that it will always be for the better and the sake of your own happiness and in turn, a huge chance that it will make the relationship stronger, healthier, and much deeper then it was before.
If you need help in figuring out what you need to do in order to define the relationship... there is loads of help available. This is one of the best things you can do to build a strong relationship with your partner, and it is well worth the effort!