The Power Struggle occurs in all Love Relationships. Our relationships usually shift into the power struggle towards the end of the Romantic Stage of a reationship - when people laughingly say they are no longer in the honeymoon phase of their relationship.
In the Romantic Stage of your relationship, you and your partner were brand new to each other. You both presented the best of yourselves to each other, and what you didn't know about your partner, your mind filled in the blanks with how you thought the other person ought to be.
Your relationship moved into the Power Struggle stage when you made a commitment to each other, perhaps to start being exclusive, or when you moved in together, or got married.
You may recognize that you and your partner are in the Power Struggle when you notice that you are both triggering and reacting to each other. You may notice that much of the time you are feeling angry or maybe hurt, or disappointed.
This is the time when many couples enter the therapist's office.
Some people stay stuck in the Power Struggle for many years, or even their whole relationship. But once they realize what is happening in your relationship, then they are empowered to make changes.