I'm quite sure that Max's problem is that he misses Riley.  I hate to
see these guys grieve.  It takes a few weeks for the survivor of a
bonded pair to finish mourning.  But sometimes they are never the same.
It's not necessarily a change on the survivor's part but more so the
difference in the relationship.  We as humans do not necessarily behave
the same way around each different friend.  Sometimes we have our wild
friends, sometimes the tame and grounding type friends and we behavior
reflects the differences in these relationships.
[Posted in FML issue 4524]