Yikes! As I hit post, I thought to myself that bringing up the "c" word again would probably just cause some kind of trouble.
There is a very important distinction to be made here. To say that the OP is cuckolding her bf is just plain wrong. The definition of cuckolding is being unfaithful, which had nothing to do with ethical poly, which the OP is practicing. The connotations of cuckolding in the modern , fetish-y way it's used are that the female partner is purposefully humiliating her male partner, emasculating him. Again, nothing could be further from the truth of the OP's actions towards her bf. I got really offended at some of the presumptions that were thrown around earlier that implied her behavior was inherently hurtful or that she'd put him in a bad position. She's been respectful, caring, honest, supportive, and loving -- NOT cuckolding in the least.
However, there is the reality and then there is the fantasy. While I disagree with much of what DH said earlier in the thread, he also said "He may embrace the cuckold/turned on / hot wife thing". And the fact that they are now doing roleplay and the bf is getting off on being teased about the lover (a very common mild intro to kinky cuckolding play) leads me to the inescapable conclusion that DH was right on that score! I'm surprised, the OP is surprised, the bf may well be surprised, but at least one person did predict it and I felt it only fair to point that out.
The thing is, it's not real. To say she "is cuckolding him" is like saying of a couple who enjoys consensual non-consent (in other words pretend "rape" where the person being "raped" in fact loves the idea and could call it off at any time), "he is raping her". Putting it like that makes it seem like something abusive and wrong and unwanted is happening. Rather, in that situation you would say "they are enjoying the fantasy of rape". And in this situation, at least to some minor degree that may or may not go any further, the OP and her bf are enjoying the fantasy of cuckolding. They are *playing* and if that's not explicitly acknowledged in the way people talk about it, it paints entirely the wrong picture.
"She has also told us that she likes to be tied up and given anal sex when she is with her lover and that her bf waits at home to give her a cuddle when she gets back....That to me is a cuckold." <-- I completely disagree. It's what you make of it. Would it not be cuckolding if she wasn't doing anal with her lover? Would it not be cuckolding if her bf wasn't sweet to her after because he loves her? What makes this cuckolding? Nothing. I mean, maybe you're not tring to do this, maybe it's just a poor wording choice or me misreading, but all I can think when I read this is -- what the heck is up with throwing this label on her bf, which he may or may not ever choose to embrace for purposes of roleplay, as if it's some essential thing about him, just because certain elements of their situation outwardly resemble a trope? This situation, at its core, is just a matter of a woman with two lovers who loves sex, and to insist that that must be emasculating to the one who's gentler comes off, ironically since I'm sure you don't mean it that way, as anti-sex and anti-gender-equality and anti-poly. If they choose to embrace the potential to read that into the dynamic as a form of roleplay, awesome. But don't confuse play with reality.
The difference is that in the fantasy, the partner playing the role of the "cuckold" has no choice in what's happening and doesn't like it, when in fact the bf could call off this form of play at any time. The difference is that in the fantasy, the partner playing the role of the one doing the cuckolding likes to see her partner squirm and doesn't respect him, when nothing could be further from the OP's reality outside, perhaps, the bounds of this new roleplaying they're doing. The difference is that there is not in fact anything inherently humiliating or emasculating about having rough sex with one guy and coming home to another... otherwise, there'd be a LOT more poly men calling themselves "cuckolds".
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.