wellbeing

It seems reasonable to be glad something has happened or not happened.

Depending how it's understood, though, gratefulness makes dubitable assumptions about the existence of free agents with the power to bestow goods upon you, that is, assumptions about some deity or persons with free will.

Of course, gratefulness can play a helpful role in harmonising human interaction insofar as it implies a belief that the people to whom you are grateful harbour good will towards you.

If you believe others (or gods) have good will towards you, then you might feel favoured and you obviously have reason to be happy.

Having abandoned belief in free will and gods, though, you are left feeling glad that, for whatever reasons and causes, both other persons and the nature of things happen to be treating you well.

Further, you are well aware how precarious this situation really is, and this gives you an additional reason for gladness.