As stated I know the answer to the title is a hard no, but hear me out.
I started a side business setting up video game clubs for libraries and schools in my area while I was in college. Eventually I graduated and picked up a full time job and no longer had as much time to answer emails, develop content, troubleshoot, etc. I tapped a couple of friends to help me with the process. Over time, I handed over more of the work to one friend in particular, we'll call her Rose.
Rose has been handling the lion's share of the business under my supervision for about two years now. She's just starting to job hunt, and her experiences working for me make up a decent portion of her work experience. If the case were that cut and dry I'd certainly be willing to be a reference for her due to her great work ethic and the quality of work she's been producing.
But there's a twist; we're girlfriends as of about five months ago. Now there's a clear conflict of interest, even though at the time she started working for me and for the duration of about a year and a half we were just friends.
Can I ethically be a reference for her now? I'd like to think I can be objective based on her performance before we got together, although I accept that I probably carry some bias. Obviously it looks worse if she can't put someone down as a point of contact for the work she did, but I'm not sure if I'm "allowed" to speak about her now. If I can, should I be disclosing our relationship or not?