If there’s no attachment, there’s needless of letting go.
If there’s attachment towards either something pleasant or unpleasant, enjoyable or painful, then know that everything is impermanent.
If one knows what is non-attachment towards what is pleasant and enjoyable, then one can fully appreciate and enjoy what is pleasant and enjoyable, but will be able to let it go in peace when impermanence strikes. If there’s attachment and one doesn’t know how to let go, then there will be dissatisfaction, disappointment, unhappiness, hurts or painful sorrow upon losing what one likes very much, that is pleasant and enjoyable. And there’s nothing wrong with that, just that one needs to know that even those dissatisfaction, disappointment, unhappiness, hurts or painful sorrow are also impermanent.
When one is holding onto something unpleasant or painful, and one cannot withstand the unpleasantness or pain, one can choose to let go of it, by putting it down without hurting it, without regret of letting go something that one likes very much, but it’s unpleasant and painful. A lot of time, most people would just react spontaneously if they dislike the unpleasantness or pain, or couldn’t forbear the unpleasantness or pain, and would be throwing away immediately whatever that appears to be unpleasant or painful to oneself, and cause damages to that either wittingly or unwittingly.
There’s nothing wrong if one decided to continuously holding onto something that one likes very much even though it’s unpleasant or painful, but then, one must also accept the consequences of that and endure all the unpleasantness or pain due to unwilling to let go something that appears to be unpleasant or painful to oneself, without expectation towards this unpleasantness or pain will change or disappear, but allowing the changes to be what they are, not necessarily the way that one would like it to be.
It’s everyone’s freedom for whether they want to let go, and be free, or they don’t want to let go, and accept the consequences of one’s action and decision of not letting go.