Even when everything seems to be going right in a relationship, keep checking: Have I become dependent? Have I become exploitative? Have I started holding expectations? Has the other started holding expectations? Is the other blocking my view of the larger universe? Has the other become too central to my mind, my thoughts? Has the other started occupying my inner space to an extent that may be called unhealthy?

These are the things that you should check for when there are no troubling symptoms. Often when the symptoms appear, it is already too late.