You see, this is where we disagree. I think it is possible to meet someone kind of like my partner, Jules. She'd be perfectly happy with this and just... waiting, unless she grew tired, which she wouldn't do with an established partner. Not having sex for this reason with a partner wouldn't bother her much because, while she needs sex, she doesn't need sex from all of her partners, all of the time. And she doesn't care why they don't want to have sex.
She wouldn't feel the same as we would about it, so it's not inconsiderate or unethical to treat her this way.
I think it's a matter of compatibility. The couple needs to find people like Jules who can work with these ebbs and flows, without negative feelings.
Haha, I don't think this couple NEEDS to find another partner for the husband right now. It seems like either Husband breaks up with the OP, or he tells her there is no sex at all, for the foreseeable future, take it or leave it, and OP agrees (in a Jules-like fashion). Then, OP goes ahead and accepts the breakup, or agrees to the no sex for X amount of time, doesn't break up, but goes and finds another partner who can actually have sex.
Without more information from the OP, about whether this is a "her problem," (avoiding dealing with the situation and just going along passively and resenting the missing sex), or a "him problem," (bf going along with wife's demand he stops having sex with OP until she damn well tells him he is "allowed" to), we really can't give proper feedback and advice.
Either way, we can guess that the newly-delivered wife would rather hubby keeps to home, takes care of her and baby, and if he's gonna have sex at all, have it with her. It could be she's decided she doesn't want to do polyamory at all until the baby's needs become less urgent.
If I were the OP, I'd ask about this. I once broke up with a very nice man, against his wishes, because his wife was pregnant (and they had several other kids/stepkids between them), and *I* wanted him to prioritize his family. The problem wasn't sex, it was that he wanted to keep seeing me, but was so busy and distracted with the family, he kept being late for dates, or breaking them.
I don't necessarily think a style that would lead to the happiest outcome for OP, would match the happiest outcome for the wife. For that reason, it wouldn't be the happiest outcome for the wife. So again, I think this is a case of the couple accepting they do poly this way and that there are fewer people who can be content with it. I don't think it's a case of them doing poly the wrong way. It's their way.
Again, we don't know if this couple really don't want him to have sex with OP for an undetermined period of time, or if it would be fine, if OP would just pull up her big girl panties and ask.
I think people know themselves well enough to know when they could cope vs when they could thrive. I think the decision to take sex off of the table is the couple acknowledging the wife cannot thrive while sex is still on the table between OP and Hinge.
Who knows?
Sure, she should find a more compatible partner.
She certainly could, once she asks the important questions and gets a clear answer and it's not an answer she likes. Living in a grey zone indefinitely is not acceptable to our OP (even tho it may be to a person like Jules, who has other partners to have sex with).