Most people get this concept wrong because they have a very idealized version of what a romantic relationship is and how they should conduct themselves while in one. They think that their partner's happiness is a direct result of their own actions but this is simply not the case. You can make a person smile and make them feel good but if they are happy or not is something that is totally out of your own control. You are a completely different entity from your partner on a completely different and separate Spiritual journey. You have chosen to walk together on your life's paths but your Spiritual journeys will always remain separate. Your happiness is a result of how fulfilled you are on your Spiritual journey and not something your partner is doing or not doing while you walk your paths together. Therefore you need to take responsibility for your own Spiritual journey, and find happiness within yourself instead of projecting this responsibility onto your partner. They will never be able to accomplish that which you can only accomplish within yourself.