Choosing a partner is probably one of the most life changing and difficult decisions we will ever make. We meet an infinite number of people in our lifetime, yet we choose that special person to share our life with. We don't normally begin a relationship thinking, “Looks like he would be a perfect first husband”.
We initiate a formal relationship once we feel secure and in fact certain that that person is the right one for us. Nonetheless, there is a moment when the novelty fades away and the weight of a routine begins make us feel like we grow apart from each other. It is very common to see couples coming into therapy because they feel they have a "professional relationship" rather than intimacy and a personal connection.
Sometimes it's just an act of desperation and sometimes is a premeditated preventive decision to go. There are a few that take a proactive perspective and go for the sake of self-improvement. Whatever the reason is, it is always better to address the issues in a relationship. If the decision is to leave, you will have the certainty that you have done your best.