Unprotected sex in long term r/s

I've been single for the majority of my dating years so far but I've had unprotected sex a few times before and each time ended with bv. I used boric acid suppositories and they work like a charm but I can't imagine having to pop one in after every time I have sex. I use condoms 100% of the time now.

I doubt people in a long-term relationships and married couples use condoms. My question is how does that work for you? Does your body get used to your partner's DNA after a while and that reaction stops?

I'm asking for future reference because I've always been curious about this.