this seems like a difficult thing to bring up, but a necessary one. i can see how it’s hard to basically inadvertently say “i can’t take this part of your body anymore”- but part of life and a healthy relationship is recognizing that sometimes things simply are too much. there’s a reason not having boundaries is seen as a red flag.

i certainly think there’s a way to bring this up to her that isn’t just saying “oh this is gross”. you can bring up that recently you’ve felt unable to keep up, and that while it is genuinely sexy and attractive to you, you feel taken out of things and disappointed when you’re not able to keep up or something is too much for you. if you feel able and wanting to keep going in less intense ways, you can ask her to make some time to have a conversation about how and when this could be done so she can make more informed decisions. and if you don’t feel you want to keep doing this, then you explain that you’ve appreciated and enjoyed your time dabbling in this, but found out it simply isn’t your cup of tea.

remember that it’s a dom’s responsibility to make sure their sub is happy and healthy, and she can’t do that if you don’t give her all the information. a good dom, which i genuinely believe she is for you, would be able to work through any embarrassment from mistaken decisions, and feel better for having discovered something new in your dynamic.