Does this "case" mean "instance" or "true, applicable"? I think the latter.
mo28)The attitude that nothing is easier than to love has continued to be the prevalent idea about love in spite of overwhelming evidence to the contrary. There is hardly any activity, any enterprise, which is started with such tremendous hopes and expectations, and yet, which fails so regularly, as love. If this were the case with any other activity, people would be eager to know why they had failed in it and to learn how one could do better, or they would abandon the activity. Since the latter is impossible in the
case of love, there seems to be only one adequate way to overcome the failure of love ― to examine the reasons for this failure and to proceed to study the meaning of love.
(Not a Teacher)
If I had to come up with a substitute for 'case' here, it would probably be 'situation' or 'circumstances'.