A competitive relationship is one in which two partners take a healthy spirit of competition to unhealthy lengths. In these relationships, one or both partners views the other partner's success as something to thwart or outdo rather than a joint victory.
Many people in competitive relationships, either one or both partners, tend to develop insecurities. An insecure partner feels threatened by the strengths and achievements of the other partner rather than feeling a sense of happiness. Healthy relationships work when both parties accept that the other has complementary strengths and weaknesses and use this fact to their combined advantage in life. Competitive relationships do not have an "us against the world" attitude but rather an "us against each other" attitude.
Many suppose that a happy and successful couple can work through a competitive relationship by acknowledging the fact that one may outshine the other periodically, and that difference is fine. Relationships go through various stages, so successful couples learn to navigate their varied triumphs with grace and acceptance. It is worthwhile to note that a healthy appreciation for each other lays the foundation for a healthy spirit of competition that does not damage or stifle the growing relationship or lead to hurt feelings.