Codependents usually cannot have healthy relationships without first getting treatment for their codependency. They tend to have many short-lived relationships because their neediness often becomes too much for their partner. Codependent behavior is often ingrained in a person from a young age. Therefore, seeking help from a professional can help codependents learn how to behave in order to have fulfilling, healthy relationships.
In a healthy relationship, it's normal to depend on your spouse for comfort and support. However, healthy relationships find a balance between each person's capacity to be self-supporting and independent and their ability to need support. It's when a person needs constant support and is unable to do things on their own that things can get toxic.
Getting professional help for codependency usually involves learning what triggers unhealthy, toxic behavior in relationships, and how to avoid these triggers. It's also important that codependents recognize what is and is not normal relationship behavior, and learn to become independent by finding their own hobbies, interests, and friends outside their relationship.