My in laws have been married for like decades. They see each other everyday, but they sleep in different rooms. When they talk, they always end up bickering... nearly.
See each other everyday doesn't mean "must be good". Like what miloice pointed out, couples can be living together, but not talking. To add, it can be the classic... stay together, but without the intimacy. Somehow, I find that its more important to understand and know whether one is out for the companionship or lust or (may be) love. Even if one does know what he or she wants, is it only relevant and applicable at that moment and at that point in time? That's where marriages turn bland and couples becoming disillusioned. Its all quite simply because that purpose and mission have been lost or that everyone or someone stopped believing in the earlier perceived purpose, mission and cause.
It is easy to jump into a relationship. But always remember that relationships are always easier to enter than exit. The emotional and financial cost of entry is great, but that of exit even greater.