It isn't a requirement for me to meet my lovers lovers, but it would be a red flag to me if they avoided talking about them or avoided us meeting. That would tell me that I am missing something which would tell me I need to slow WAY down on how attached I'm getting to this person.
That being said:
Originally Posted by Eslynne
I'm just paranoid because he hasn't been really clear; his behavior alters by the week, warm or cool; I don't know if this is him not feeling sure about him and me, or if somethings up with him and her
It sounds to me like you're not sure where you stand with him. While I'm sure having some imaginary significant other in the ether is a distraction for you, I would suggest not overthinking it.
As far as I can tell people in monogamous and polyamorous relationships approach meeting and showing interest about the same. If he's hot and cold and you don't know where you stand with him then I'd avoid convincing yourself that it has anything to do with his other girl. It might have something to do with her, but it might also be LITERALLY anything else (work, hobbies, friends, he isn't that into you).
Personally I think if you want to know where you stand with him then ask him that. If he says "The sun rises and sets in your eyes, your hair is like gold spun by angels, your ass tastes like French Vanilla ice cream"... that would be a good opportunity for you to say "Ok, then what gives? I find myself not sure of how you feel about me".
I'm sure you can come up with a softer version.