Do you appreciate sun for his presence? for giving you daylight? for giving you Vitamin D? :D
No, right?
Why?
Because you are used to that and you know that even if you don’t care, the sun will continue to do so.
Similarly, you know that he/she will care for you no matter what.
What you don’t know is, selfless love is rare. If someone does that for you, cherish it and reciprocate, rather than taking it for granted.
Else, one day it won’t be there.
Even sun have an expiry, but that has got time ;)