People don't always agree on what constitutes "love". In the broadest sense, it is concern for another person's well-being. You can have that concern regardless of what they do--it's when you sacrifice your own well-being for someone else's unhealthy behavior that it becomes a problem. And then, the problem isn't the "love", it's the behaviors and the self-blame or resentment that is the problem.
But I absolutely agree that keeping yourself in an unhealthy situation in the name of "love" is a bad, bad idea for everyone involved.