In the midst of what feels like unsurvivable loss, how do we moor ourselves to the fact that even the most beautiful, most singularly gratifying things in life are merely on loan from the universe, granted us for the time being?  Two millennia ago, the great Stoic philosopher Epictetus (c. 55–135 AD) argued that the antidote to this gutting grief is found not in hedging ourselves against prospective loss through artificial self-protections but, when loss does come, in orienting ourselves to it and to what preceded it differently — in training ourselves not only to accept but to embrace the temporality of all things, even those we most cherish and most wish would stretch into eternity, so that when love does vanish, we are left with the irrevocable gladness that it had entered our lives at all and animated them for the time that it did.

In The Discourses of Epictetus (public library), under the heading That we ought not to be moved by a desire of those things which are not in our power, the Stoic sage writes:

Who is good if he knows not who he is? and who knows what he is, if he forgets that things which have been made are perishable, and that it is not possible for one human being to be with another always?

Epictetus — proponent of the practice of self-scrutiny applied with kindness — proceeds to offer a meditation on loosening the grip of grief in parting permanently from someone we have loved:

When you are delighted with anything, be delighted as with a thing which is not one of those which cannot be taken away, but as something of such a kind, as an earthen pot is, or a glass goblet, that, when it has been broken, you may cherish what it was and may not be troubled… What you love is nothing of your own: it has been given to you for the present, not that it should never be taken from you, nor has it been given to you for all time, but as a fig is given to you or a bunch of grapes at the appointed season of the year. If you wish for these things in winter, you are a fool. So if you wish for your son or friend when it is not allowed to you, you must know that you are wishing for a fig in winter.

In a sentiment addressing the corporeal mortality of our loved ones, but equally applicable to the loss of love in a non-physical sense, Epictetus adds:

At the times when you are most delighted with a thing, place before yourself the contrary appearances. While you kiss your child, say to yourself, “Tomorrow you will die”; or when with a beloved friend, “Tomorrow you will go away or I shall, and never shall we see one another again.”

When we are able to regard what we love in such a way, Epictetus argues, its inevitable loss leaves in us not paralyzing devastation but what Abraham Lincoln would later term “a sad sweet feeling in your heart.” To retain the memory of love’s sweetness without letting the pain of parting and loss embitter it is perhaps the greatest challenge for the bereaved heart, and its greatest achievement.

HT https://www.brainpickings.org/2018/08/26/epictetus-love-loss/