Hi Siebe,
Let me explain what I do if I am stressed or irritated or unhappy. I try and look back to see why I am irritated. There is always some cause we can pin point it to. And this cause invariably is due to something not being the way I like it to be i.e. anicca. I don’t think one will be unhappy, irritated, stressed without some kind of cause.
But saying this, there are times when we (or even certain people who) are more prone to get irritated. Either way there is some kind of cause for that irritation. And that is due to anicca. I have not been able to find any other reason for my unhappiness or irritation or stress, other than anicca. If you (or anyone) can find another cause please share it.
Do you think an arahanth would experience any kind of mental pain, unhappiness, distress? I don’t think so. And that mental pain, unhappiness and distress is exactly the suffering an arahanth will eliminate in this life time.
This is just the way I see it.