Interesting. You did state the goodness that comes from having a regular thing going. Sounds smooth.
But.....
Having good chemistry with a regular does put you in this awkward situation, but its almost inevitable if you are going to the same shop frequently I imagine.
You sound like you have built up a good rapport with a number of fine women. Good 4 you. But im sure with such an intense few liasons, your regular feels a bit miffed (even knowing its all business) that you are choosing another.
One time, I was shown a lineup, and I was interested to meet someone new. In the lineup, was a lady I had seen before, and our previous session was a memorable one. She said 'I will let the manager know of your booking' and I couldnt say no to a lovely lady who was comfortable with me. But it doesnt matter really to me though, that session was great.
Is it possible for you to forewarn the manager when you arrive, that you have seen ... (regular) a few times, so dont put her in the lineup. Otherwise you may have to book ahead with a new lady, or choose another of your preferred shops until there are more options and time has passed
Im not an expert in this field, just floating some ideas