You can have friends from opposite sex, don't get me wrong. The situation just sounded like a date and a potential setting for an EA to happen. That REALLY can happen even without you realizing it because it gets addictive due to neurotransmitters really quickly. If you end up in an EA, you won't be as open to your W. So, I'm not going to say you have to ditch a good friend but make sure you prevent yourself from falling into an EA because it will be harmful for your progress in DB.
In my thirties, BDd 2017, divorced 2 young kids new relationship