For some people, taking care of a chore that matters to their spouse feels loving. It makes them feel warm and tingly and like a better person. Unless the opportunity to do it of their own free will is taken from them. Then it just feels like work.
For other people, a chore is always a chore. If they're feeling loving, they want to take the afternoon to do something fun with you. Or they want to give you a long, luxurious back rub when they feel loving. Being reminded that there's a chore that needs doing doesn't make them feel the least bit loving.
Some people come to marriage with a bit of a fear that love is never guaranteed and can be taken away at any moment. It's not your fault. You weren't there for your spouse's earliest years. But now you're the one he or she fears will suddenly stop loving them. Being reminded of their failure to follow through on a promise makes this fear well up inside.
Some people come to marriage with a fear of losing themselves and their freedom to make their own choices. To some extent, we all lose them a bit in marriage, and the result feels good. We're making choices together, and we like them. But if you're married to someone whose earliest years left him or her on edge about when this togetherness might become more like imprisonment, putting yourself in charge of what needs doing or when it needs doing will trigger this fear. And fear drowns out love.
Of course, you don't remind your spouse to see the doctor or vacuum the living room or ask for a raise to be mean. You do it to make sure the important stuff gets done and done fairly.
But the most, most, most important stuff is those opportunities to be loving and to feel safely loved. If you lose that, all the chores fall in your lap. If you lose that, you'll stop doing what you thought were necessary chores to go find someone new to love you. If you lose that, it doesn't matter whether your marriage was fair, because divorce almost never feels fair.
Nagging your husband or wife? The costs are never worth whatever it might gain you.