The vagueness of the term certainly leads to as many different interpretations as there are clients and providers.
However, I think a general impression can be culled from our individual ones: That BFE is just as much (if not more so) about compassionate mental-emotional affection and interaction as it is about whatever else may take place.
For me, it means that we spend time together and there's a general ebb and flow with our physical interaction as opposed to having a laundry list of physical acts to take place. A fair amount of time could be spent hand holding, cuddling, talking about the great mysteries of life, etc --- generally behaviors one may expect in an established relationship versus what behavior one may expect from picking someone up at a bar.
I think I would be remiss if I didn't mention a fantastic piece about BFE by @tylerthebadwolf for thought catalog - https://thoughtcatalog.com/tyler-darlig-ulv/2017/05/what-being-a-professional-companion-really-is-because-it-isnt-sex-work/