Affection
Etymology
From Latin "afficere" (to act on, influence), from "ad-" (to) and "facere" (to do), via "affectio" (a disposition, state of feeling). At root an affection is simply a way you have been "done to" — a state produced in you — which is why we also speak of physical "afflictions" from the same source.
noun · /uh-FEK-shun/
A gentle, warm feeling of fondness or tenderness toward someone.
What it names
The mild, steady warmth of caring — the everyday temperature of love rather than its heat.
Example
There was no passion left, only a deep affection that made the long marriage comfortable rather than thrilling.
Related idea
Affection is calm and abiding fondness; love runs wider and deeper, encompassing desire, devotion, and sacrifice that mere affection never demands.