Completely alone, unless locked up up in a room away from nature perhaps.
Deep hole in ones spirit when something close to ones heart moves on, yes loneliness and loss not quite alone.
Quirky thoughts often interrupt thought when one of the animals I have had close to me appear, like a quiet visit saying remember me, what fun we shared. A few tears will well up in a moment cherished.
I always think too much and yeah, sometimes there's tears.
Overthinking not a problem, those first weeks after a pet departs I am best left alone. One never forgets....