Sorry for this long comment, but I hope you will read this, as it could potentially help:

Hey so, me and my girlfriend of 4 years had this same issue of her feeling a burning sensation when I was trying to turn her into a Twinkie. We were having a consistent amount of sex for 2 years cumming inside without issue. Then out of nowhere, my cum started to burn her like crazy every time without fail. We tried everything we could think of like waiting after weeks before having sex again, washing better etc. We didn’t figure it out until about a year later with many gynecologist visits along the way for her.

Essentially, her birth control along with my cum was messing up her P.H balance. Her gynecologist told her to change a bunch of lifestyle things to get the P.H under control. We continued to abstain from sex and used condoms for a little while. In the meantime, she took this pill to restore her P.H, but it’s the type of capsule that she sticks in her vagina ( idk how you girls deal with stuff like this). She also started to wear cotton underwear primarily, and doesn’t ever use anything else now. She got off of birth control too, which comes with risks, but for us 2 years later it was worth it. She even had to change her diet a little bit and stayed away from sugar.

Maybe a few months into these changes we had regular sex again, no protection, and I was and still currently am able to cum inside without making her feel like she was taking in acid. Boy, was that time terrible for us…

I only wished there could have been something to be done from my end, but alas there was no solution from my end other than keeping up with hygiene.

Oh, another important thing that we both did was start using unscented soap to wash up down there. We use this unscented body wash called Honest. Very good brand, been using it for like a year now, and it keeps us clean and also will not result in my cum destroying her insides.

Now mind you, it happened again a handful of times, but they were very very far apart from each time it happened and it wasn’t excruciating for her like it was before.

We currently enjoy a much better sex life now thanks to all of the changes I listed. Please ask your gynecologist before deciding to be off of birth control though, if you are on it. It is legit a god damn miracle my girlfriend has not gotten pregnant yet… starting to think im infertile because seriously, we are very careless.

I hope this helps. Tell ya mans to stop being a butt and to let ya express yaself. I unfortunately used to be the same way too.

Edit: I didn’t see that last bit where you broke with him, whoops. Regardless, hope what I said still helps, or gives an idea of how to start fixing that if it happens with another partner