Couples counselling/relationship counselling: In this type of therapy, the therapist acts as an impartial outsider. The therapist will facilitate discussion between you and your partner and may also help you both identify any triggers or patterns that are causing problems in your relationship.
Individual therapy: If your partner will not attend couples counselling, or you would rather discuss things alone, then individual therapy may be beneficial. This type of therapy will allow you to discuss your own personal feelings and enable you to tackle personal issues, such as jealousy or anger problems which may be at the root of your relationship problems.
Self help
You may find the following books helpful:
Human Relationship Skills by Richard Nelson-Jones
This can be used as self help or in client work. It contains a comprehensive guide to all the relationships with have in our lives (including work colleagues, friends and sexual partners) and advice on how to manage these relationships in a healthy and fulfilling way. A lot of coaching techniques are contained within the book, which could be helpful with people who like to do exercises and worksheets.
Stop arguing, start talking by Susan Quilliam (Relate)
Passionate Marriage by David Schnarch
Very psychologically solid and explicit, this book centres around the sexual arena within long-term committed relationships but brings it all alive.
The Mindful Couple: How Acceptance and Mindfulness Can Lead You to the Love You Want by Robin Walser and Darrah Westrup
This guide for couples is based on a simple concept: Act out of kindness, love, and acceptance, and you will open your relationship for the creation of greater kindness, love, and acceptance.