If you haven’t tried having rough / very firm / hard sex with your wife, try a little experiment.
The next time you have sex, without particularly asking permission or announcing your intention, just pound her harder than usual. You can get her off first by fingers or tongue as the curtain raiser, but once it’s P in V time, just climb on top of her and go hard at it. Don’t worry about whether or not she will like it or will orgasm, don’t worry about how perfect your orgasm will be this time. All you’re testing out is how she responds to getting vigorously screwed. You can work on the finer points later.
If you’re worried about really injuring her relax a little. Vaginas are pretty solid things, they are after all designed to have 8 pound babies push out of there. Unless you have some sort of porn stunt cock, it’s not really possible to really injure her if you have enough lubrication down there. You cock is going to break before a vagina does. So give going rough a trial.
If she likes it, a good sign is her being unusually cuddly after sex. Another thing to look for is what is she like the next day? Happier? Doting on you? Smiling at you more? She cooked you a favorite meal? She made not even realize she liked it as much as she did.
Several years back I started trying rough sex on Jennifer. The first few times I tried really pounding Jennifer hard I was extremely nervous about it. It really didn’t seem a very nice way to treat someone and I honestly expected a negative reaction. I only starting thinking about doing it based on coming across a few things I read saying women liked it. But even though I felt emotionally awkwardly for doing it to her, I tried it anyway. I was quite surprised to find that my sweet shy naive polite quiet wife lapped it up like the head cheerleader. Plus instead of our usual post coital routine of me snuggling into her, she snuggled into me every time I tried it. Not once or twice… every time. The next day she would be just all giggly and a little silly with me. Huh… who knew.
So even though I was surprised by her reaction and I felt uncomfortable doing it, I knew enough to recognize that she did in fact like it. Over time I grew less worried by it and started really enjoying her reaction to it. It’s still not my favorite sort of sex, but I do enjoy it and she really likes it so it’s on the menu. It’s not the whole menu by any means, but it’s a reasonably frequent choice for us.
So give it a trial run if you haven’t already. She may just like it. And if you haven’t talked about a safeword, consider “ow!” the safeword for now.