My relationships have followed this pattern. It’s worse when you have children together. Discussing relationships with a friend, I coined the term ‘male drain,’ which accurately explained the mental exhaustion we each experienced in keeping our respective partners for years. The point about co-dependency is bang on. I would even go further with this observation: after extricating myself from my last serious ‘male drain’ relationship I experienced a form of withdrawal. It is only now, 18 months later, that I’m really feeling the benefits to my mental health, energy and overall happiness 😊