chronic stress + memory issues
Not gonna speak on traumatic memory loss/memory repression because I don't have that, but here's some fun things that could happen to your whumpee's memory if they're just really fucking stressed:
Everything feels years ago. Yesterday? Would not be able to tell you that happened 24 hours ago. I thought it was last year.
In a similar vein, I thought that happened yesterday but no it happened in 2023.
Mixing up the order of events. You remember it all, it's just scrambled.
Coming up with nothing unless someone prompts a memory.
Thinking things that happened this morning happened yesterday or some other time in the past because anything more than 5 minutes ago gets lost in time.
Having to piece your week together like a puzzle. "I did A and Z, so at some point I must have done L, wait no I did D first, then I did... hang on that isn't right". It's not easy and takes way too much thinking. You will likely just give up.
The classics: walking into a room and forgetting why, picking up your phone to check the time and doing everything but that, starting a sentence and going off on a tangent only to never return to your original point.
Trying to recall things for a class or exam won't happen. It goes in your head once, leaves, and never returns.
You'll know half-facts and out-of-context pieces of information with no surrounding context to help you know why you know this or figure out if you've just made it up.
It becomes very easy to convince yourself that people you see regularly (your neighbour, a shopkeeper etc) have had involvement in your life or personality traits you may have just made up because you can't remember why you think that about them, or vice versa- they do have these traits or shared history with you and you've convinced yourself it's not real because you don't remember where it originated.
Old memories you do have are more likely to be memories of recently looking at a photograph of the event rather than the event itself.
Old memories are hazy and few enough it's easy to convince yourself they may never have happened.
Old memories do not feel like they belong to you. They don't belong to anyone else, either. They're just images and facts in your head.
Whole years will feel like they're missing. Major friendship changes, periods of work or school. You won't realise they're gone until you try to look for them and come up empty handed.