Thanks for writing.
That can be difficult to hear that your partner is having unprotected sex with other people. It’s great that you both got tested after.
In terms of the bacterial vaginosis, it’s unlikely to be affected by your partner’s activities. Bacterial vaginosis is not sexually transmitted, or passed between partners. Bacterial vaginosis is an overgrowth of normal vaginal bacteria (so it’s not “bad” bacteria), and it’s your own bacteria (so it didn’t come from anyone else).
It’s common for women get bacterial vaginosis whether they are sexually active or not. Many women will get bacterial vaginosis frequently for a few years, and then it can settle down and not come back. Sometimes women who have multiple sexual partners can get bacterial vaginosis more often, as they are being directly exposed to different people’s bacteria. You would not be exposed to other people’s bacteria through your partner (normal bacteria can’t be passed indirectly, only STIs can be passed indirectly).
Lastly, just a reminder than it can take up to 3 months for STIs to show-up in testing. If you only got tested a few weeks after your partner had other partner’s, it would be good to get re-tested after 3 months just to be sure.
Hope this helps. Please feel free to comment below or submit another question as needed.