Peak - I can’t say you are wrong about what will eventuslly happen, but I don’t think you are correct about the lack of sexual intimacy. It is possible that Sue and Steve continue to enjoy a high degree of sexual intimacy, despite the lack of vaginal sex. Much of this dynamic they share is highly sexually focused. In some ways, it appears that Paul functions, in the marriage, as a physical and emotional “fucktoy” for thr triangle. This is not to deny the reality of sexual and emotional intimacy between Paul and Sue, but those things, far from detracting from the intimacy between Sue and Steve, could be functioning as an enhancement to their own intimacy.
The denial of sexual contact is itself a sexual arousal stimulus for both Steve and Sue at this point. The teasing is functioning the same way. While they mostly don’t have sex with each other, and Sue’s primary sexual contact is with Paul, the sexual relationship between Steve and Sue is an integral feature of all of Sue’s sex with Paul. Then there are the various instances of outercourse between Steve and Sue, with her supervising and assisting Steve’s masturbation with regularity, sometimes even masturbating along with Steve. The sexual activity is redefined away from genital contact, but their brains are all about each other quite frequently. I wonder whether Sue thinks about Steve while she’s having sex with Paul, even to delight in the naughty notion that she is giving Paul something she is denying Steve, and whether this increaees her arousal and pleasure in having sex with Paul, in the same way that Steve is aroused to a hair trigger by how Sue is denying him while lavishing her sex on Paul. Since this is by consent, and both seem to be getting off on it, it may not be a threat at all to intimacy.
Now, Steve says that he’s great with things as they are, with the mixture of pain and desire that form the arousing emotional cocktail for him, but that he’ll also be okay with giving Sue more sexual contact, should she decide that’s what she wants. Right now, Sue is riding the cuckoldress high, enjoying all aspects of ger situation, including the acts of teasing and denying Steve, not just for their effect of Steve, but for her own arousal. What will be the test is to see what happens if Steve starts to want more sex, and Sue does not want more sex with Steve, but would prefer to deny him in his more intense yearning. Will that happen? Will Steve resent the denial at that point, or will he become even more aroused by it? Would Sue cave in and have “obligation sex” with Steve in such a scenario, and what impact would that have on them?
It’s a very complicated sexual cocktail, and ultimately, as long as Steve and Sue keep their marital relationship as the top priority, I think they can negotiate whatever comes along to deepen their connection.