Happiness, as a state of satisfaction with life, is not an emotional state.

It is possible to be a perfectly happy person, i.e. to be fully and completely satisfied with your life and still, in certain periods of your happy life, experience: despondency and sadness, sadness, despair, desolation, helplessness, vulnerability, depression, anxiety, excitement, horror, and many other things that are called negative mental feelings.
And on the contrary, you can be an unhappy person, not finding satisfaction in your life and at the same time at certain periods experience: optimism, joy, bliss, admiration, relief, calmness, euphoria, and much more, which are called positive emotions.
A mentally healthy person responds to a negative situation with negative emotions, and to a positive situation with positive emotions.
To assume that happy people experience exclusively positive emotions is tantamount to the delusion that all unhappy people experience exclusively negative emotions.
As a conclusion I can say that mental health is not a condition, much less a guarantee of a happy life, just as human health in general is not a guarantee of a happy life.