Often we come into relationships with expectations on how life will be, based on our own family of origin. No two families are the same so it is natural that at least some of our ideas will be different from those of our partners.
Holding different opinions in itself is not a problem; disagreement can be a healthy aspect to all relationships. However it can be that the relationship gets strained to the point that it isn't functioning at its best and instead is producing self-reinforcing, unhelpful patterns. Sometimes it is the way that we argue rather than what we argue about (the process rather than the content) that is the problem.
Relationship therapy can be helpful in this situation for both individuals and couples, as it looks at what lies behind current difficulties, paying attention to both the past and the present in order to bring about change.
Often relationships can experience difficulties because of external factors (extended family, financial struggles, employment, mental health problems). Although therapy cannot change these issues, talking in a neutral space can help couples reach an understanding and find an agreed way forward.
Although it is hard to predict the length of time couples will benefit from therapy, it is likely that initially we would meet weekly, then bi-monthly and/or even monthly.