I've never understood this! I practice non-monogamy in my persona life, and I have always said that one person cannot be your be all end all.
You need many fulfilling sexual and romantic relationships in your life. I can only provide so much to the clients in my life, and it excites me to give a reference or help facilitate an experience with someone else. When it comes down to it, if my client is happy, I'm happy. I can't ever imagine being upset because my client or my partner gets on with someone else. The concept is so foreign to me. I've seen it happen, or even in reverse, where my clients make a point to try and assure me they aren't seeing other providers. Why not? People aren't property! Jealousy just isn't an emotion I have very often, and it always pains me to see situations like this, ESPECIALLY in a provider/client relationship! One of the reasons you're paying us is to avoid drama like that. I think it's unprofessional from a provider standpoint, on top of my other points.
For once, I agree with something Dawn's said: "but i would never make a client feel bad for seeing other escorts or women. ever. it's manipulative and petty, and i'm disappointed to see how commonly this tactic is used in this industry. the sad thing is that it works, really well. and it really makes me lose respect for the men that it works on." Bang on! It's just super gross all around. I couldn't imagine working within an industry where my job is to make people feel GOOD, and turn it around and make it such a negative point.
I'm sorry you're experiencing this and I wish you luck!