I have learned and continue learning to take nothing and no one for granted.  When one forgets to  appreciate all that life gives us, then one will settle into complacency, routine, boredom and just take people and things for granted.  This is suicide for relationships and when it's happened to me where the other person fell into this complacency, I didn't have the power to awaken them so I'd leave.  I'd rather be alone than lonely with another.  I finally found someone who is awakened to what's important in life and it's a miracle that I never stop feeling gratitude for.