Here are three things you can do to reduce the amount of competition in your relationship or help a partner who is destructively competitive:
1. First of all, recognise that a competitive personality is a sign of emotional weakness. The winning is designed to avoid the intolerable feelings of losing and failure. Therefore show compassion to somebody who is very competitive.
2. Deep down, somebody who is driven by competition is competing for love because they feel that they lack it themselves. The winning makes them feel better about themselves. Anything you can do to help them find self-love will reduce their need to compete.
3. Notice where you are competing with your partner. This can be very subtle, but enormously damaging to your relationship. Strive for equality in your relationship. This means valuing your partner just as much as you value yourself and avoiding any temptation to judge them. Love always appears when equality is present (and competition naturally falls away).