kleinbl00 said an equal relationship means "getting what you want without giving up anything you want to keep" -- I wish I had asked what does that mean or give me an example, but it was time to go. To me, equality in a relationship is a feeling -- it just feels equal, there are no tallies, no quid pro quo, and most of all no resentment, no resentment generated passive-aggressive behaviour or critical sarcastic comments. Some couples have to work it out on a tally sheet -- and that's okay as a way of building trust. Others just give all they can naturally and spontaneously and consistently and it feels kind of equal even though you're both willing to give even more than your share.
To be fair, that answer wasn't originally mine; it came from a book on relationship advice I read maybe 25 years ago. I had recently ditched a relationship where I was paying for everything because she wanted to demonstrate her "financial independence" from daddy - the same daddy who flew us to Kauai for two weeks for her graduation, the same daddy who guilt-bought cars for his kids. The advice came from their take on how unequal financial partners can have an equal relationship - if she's a barista and he's an investment broker, it's pretty dumb to expect them to split the tab down the center. What's important is that both partners feel they're on an equal footing, so sometimes she treats at Wing Stop, sometimes he treats at Ruth's Chris. The argument went further: when cohabiting, there should be a joint account and two private accounts so that the money responsible for maintaining the mechanics of the relationship is sorted while the money responsible for maintaining the joy of the relationship exists within each partner's sphere of autonomy. I've seen a lot of relationship structures. I've seen a lot of different ways people make each other happy. And the through-line on "unhappy" is always one partner giving more than they think they're getting. There's no point in arbitrating where that line is or how much laundry-folding equals one mowed lawn or whatever; what matters is that whatever one partner needs is given freely by the other. You want an example? My wife's needs are simple: (1) don't fuck with her pillow (2) don't leave your socks in the living room. Need something ornate sewn by the evening? No problem. On the other hand, she lives in dire fear of the written word so if I vomit 250 words for a job posting, she sees that as saving her days and days. It would take me several weeks to accomplish anything with fabric but I can spit out limericks in near-realtime - what I give up is nominal but it means the world to her, what she gives up is nominal but it's huge for me. (1) don't fuck with the pillow (2) don't leave your socks in the living room is much more achievable to me than (A) guess what mood I'm in and respond properly or else I will rip the remote from your fingers and fling it at the wall without so much as a word of warning BUT I have seen, been around, befriended and counseled people who fucking need to scratch that crazy-ass "I must date an unstable histrionic bitch" itch.
For me the nuance I'd add to this is tradeoffs can be ok, but they're done in the open and generally comparable. Not "if you come to Christmas at my parents I'll let you go out with your friends next weekend" but more "I'm training for a marathon which means I'm doing fewer of the communal tasks so I'm going to make sure to give you time for your hobbies when the race is past." In my mind it's healthy to give up some things I want to do, but drawing the line at things that are important to me even if they aren't essential. Running a marathon is a want. Running at all is important. Doing some organized races is important. Doing a specific one is not. But even then if I said I wanted to run a marathon next fall and was asked not to, it should be because of something important to them. Like if the race is a Saturday but her brother is getting married Sunday and she doesn't want me to be useless and exhausted at the wedding? Ok. Doesn't want me to because she wants to hold that weekend in case it's peak leaf color change? Not so good. no quid pro quo