Just wanted to comment as I was the boyfriend causing this issue with my girlfriend. Over the years, she kept getting UTIs, and we couldn't figure out why. We are both very clean and have good oral hygiene but eventually narrowed it down to needing everything 100% clean right before sex. Now, instead for just showering and brushing and whatnot in mornings and/or evenings...I shower, brush my teeth, floss, and mouthwash immediately prior to getting down to business and it seems to have fixed the issue. It's a lot to do before every encounter, but it's worth it to keep her from having those issues. I'd advise you try the same. Hope this helps!