Your post contents themselves deserve a response, but to answer the question: I've never bothered thinking life is unfair, I learned this lesson early on as an eldest sibling (and it seems like a lot of other eldest siblings I talk to are slightly more in tune with unfairness than non eldest siblings, but this is anecdotal and I'm not willing to defend this observation)

Life is obviously filled with things that feel fair and unfair, but ultimately fairness is not part of the rules of our reality so there's no need to determine its presence or abscence.

To speak to your own response, it's super easy and feels great to imagine those who we feel have wronged us have been suffering ever since we left their lives. Rarely does this ever actually play out that way, nor is it healthy to rely on this line of thinking to find closure, peace, satisfaction, etc. It is more realistic to expect their lives to be fulfilling their goals on some level, and its likely they aren't miserable at all.

I have no idea what you're saying after the first section, but there are people out there all along the "is okay with a non ideal partner" scale out there. You can have your flaws and have a partner and a healthy relationship, and anyone worth your time will consider any progress you have already made, even if that's not always enough to make you the one they want to be with.

I don't want to make any further statements as this is already too general and assumption heavy, and you do not deserve to be told what to do without an ounce of actual attention to your life. I can guaranteo you're not alone in the problems you are facing.

I've always found riding the waves of life with attention to my goals has worked in a way that leaves me generally satisfied with the process.