Why are pleasant feelings "stressful" & "unpleasant"? I read the following in the internet:

All feelings are categorically classed as unpleasant in the
Dhamma...'Three feelings have been spoken of by the Blessed One: a
feeling of pleasure, a feeling of pain &amp; a feeling of neither pleasure
nor pain.,,,Now in what connection was this stated by the Blessed One:
&quot;Whatever is felt comes under stress (yaṃ kiñci
vedayitaṃ taṃ dukkhasmin)&quot;

Why are pleasant feelings &quot;stressful&quot; &amp; &quot;unpleasant&quot;?
If all feelings are unpleasant, why are some feelings called &quot;pleasant&quot;?
This is what it says in MN 44 sutta.

&quot;Pleasant feeling is pleasant in remaining, &amp; painful in changing,
friend Visakha. Painful feeling is painful in remaining &amp; pleasant in
changing. Neither-pleasant-nor-painful feeling is pleasant in
occurring together with knowledge, and painful in occurring without
knowledge.&quot;