A wolf's affinity can be found by going to a wolf's page, scrolling down to Vitals and clicking Affinity. This will show you a detailed report of how your wolf feels about the other wolves in your pack.
If your wolves dislike each other, pack happiness will decrease. High pack happiness helps wolves regain health quicker.
A wolf's affinity can change for several reasons:
-either you bought Make Friends for 10 apples to improve its affinity, or
-you made another wolf which it disliked leave the pack, thus improving its affinity. (probably what happened in your case)
Winter Month: 2 
Night 
Fog Moon: 
