I'm a little late to the discussion, but I'm glad that you have accepted that despite the inexplicable change in your relationship, HipsterBoy has set limits that you want to honor.
Trust me, I know what it is like to see something that you think no one else sees in terms of relationships. "It doesn't have to be this way! There's no good reason why we can't go back to how things were!" Life is cruel and unfair sometimes and despite the ability to imagine what would happen if certain life events hadn't occurred, those events did occur and can't necessarily be bargained back. It's a hard lesson, but you get that.
It's also hard to realize that while someone might want to discuss an issue, it's not necessarily because they want to achieve the same end result. A lot of times, especially if they do care about you (whether it's romantic/erotic love or friendship love) they'll try to discuss things with the idea of letting you down easier or simply trading time talking to be nice, but not with any chance of changing their mind. It's counter-intuitive, but sometimes people don't always want to do things for the reasons they hint they do. It's not lying so much as well-intentioned adjustment.
I'm also right there with you on the "we went too far too quickly, and I can't see us going back" idea. Some might consider it pouting or selfishness, but I don't. I've been there. Yes friendship is the basis for a long, healthy romantic relationship. Yes, I get the logic of "if you wanted them for a lover, surely you'd like to have them as a friend." Bu it doesn't work that way for everyone. Sometimes it can be like re-opening a wound every time you attempt that friendship. Or it can just be too awkward, because you don't want to be perceived as needy or attempting to re-establish the romance, with interactions that inevitably come up. (Say invitations out to things or giving advice about their new relationships.) Sure, friends should be able to talk through these things, but in reality it can become unwieldy and cumbersome to the friendship. Sometimes you can't just go back to being friends.
Me - male, 42, poly, straight, in a serious relationship with Audrey, also casually dating.
Audrey - female, 20, poly, pansexual, also casually dating.