Why do our minds like playing in the past and reliving situations?
I think some of it is tied to our own mortality. As I get older, I become more cognizant of time, and of the fleeting nature of our existance. This also gives me more appreciation for my life, and possibilities. This appreciation makes me enjoy going back in memory lane, and I can be *incredibly* nostalgic.
I just...can't quite describe it...but it's almost like a way to detach myself from 'me' -- by going back, I can sort of look at and 'relive' past events, from a detached perspective. It's not that I don't recall the exact feelings/perceptions from back then, because that's part of the nostalgia, but, well, it's history. So I'm sometimes like: 'Wow. That was me, then. Look at what I was doing. Look at who I was.' It's almost more real -- because the present is, well, a snapshot in time, which is instantaneously then the past, and I can 'look' at all of it through a wider lens when I'm going back into nostalgia.
Do we relive good situations to make us feel good?
Sure! I know I sometimes do. I don't 'judge' it though as a bad thing -- as a weakness, or whatever. Now, I don't feel I live in my past, because I am always looking ahead as well, but I really enjoy reliving happy events of my past. It can bring me pleasure, and I don't think that's a bad thing. Could it be a coping mechanism? Sure. But I think much of our existance could be coping mechanisms, if you really want to get down to the grit of it. I'd rather not analyze it that way though. If one of my desires is to live a happy, fulfilling life, remain optimistic, and remain enthusiastic and hopeful about my life, then reliving those happy moments can also add some important perspectives -- that I have in fact had a rich life thus far, and there's nothing stopping me from trying to keep reaching for that, except for myself.
Do we relive bad situations to tease us?
I think we relive bad situations/torture ourselves until we have fully worked through them, learned from them, forgiven ourselves or others, and as long as the bad situations continue to have a hold on us. So I wouldn't say we relive them to 'tease us', but rather we relive them until we are able to integrate them, tie all the loose ends in our mind, heal ourselves, let go, and move ahead. Because once they stop having a negative effect on our own sense of self and psychae, they no longer have that negative connotation. Doesn't mean the situation itself wouldn't still be objectively sucky and all of that, but one can eventually get emotionally beyond it, in the sense of looking ahead and ones mind not getting sucked back into reliving the situation.
Does this serve some function like bettering us?
Hmm.. I wouldn't put it in those words. I think it can add perspective, it can show us the larger context of our lives, and life in general, and also all of in theory should be learning from our experiences, and moving forward with more insight as time goes on. Maybe that's 'bettering us'?? I don't think any of us are actively trying to 'better ourselves' by being nostalgic, though -- it would be a potential effect of it, though. I could also see nostalgia being detrimental in some cases, though - like someone being stuck in the past and unable to let things go. But I think that's a separate issue, and it ties to my previous paragraph. The human mind is an interesting thing. Sometimes it can take a helluva long time for an individual to fully 'work through' things and be able to look to the future (and this isn't a judgement - from personal experience, with some 'issues', it's been a Process for me that covers many years) -- and I think in some cases people are never able to look ahead.
Does it affirm our identity as being separate and unique, with unique experiences?
Sure. It kind of ties to what I was saying at the start.