Why Ragapom, to me, is a "soothing ship"
... Which involves both "survivor's guilt" AND the "pair the spares" trope (very akin to Madoka Magica). In my opinion, this is both, complicated AND offers a lot of healing opportunities IF they continue the way they were depicted from THIS point onwards.
But lemme start by displaying their respective perspectives first - which cannot be done without mentioning Jax. Obvious spoiler warnings from here on out.
Ragatha's stance - and development:
From the viewer's point of view, Ragatha starts the series just as Jax would have described her trope: "The positive one", trying her best to "hype up" Pomni and prevent her from succumbing even more to either anxiety/despair or even apathy. By being overly enthusiastic and encouraging, she attempts to get closer to Pomni by offering her a shoulder and safe space, but doesn't exactly reach through to her - and not being on the same page is a continuous theme for them: It's when Pomni is so overwhelmed by witnessing her first Abstraction that she (understandably) runs away instead of helping Ragatha; it's when Pomni tells Ragatha that she doesn't "have to hype me up, I am not a child"; it's when Pomni says to Ragatha that it's "okay to be a jerk sometimes", just to tell her to calm down once she tries to confront Jax; it's when Pomni tells Ragatha that she's "not big into sports" after getting asked "Did you really not like my softball adventure?"
After what happened to Ribbit, after being told by Jax never to mention her ever again - it's only natural that Ragatha would fear "failing" and even "losing" Pomni at this point. It's pretty clear that she's overperforming, trying her best to be the aforementioned safe space for Pomni - but is only able to do so "passively" by offering, but not interfering. Which, once again, is the same that presumably happened with Ribbit and Jax before; Ribbit grew closer to Jax, they eventually had their fallout and Ragatha couldn't actively do anything for either of them, couldn't approach Ribbit or be of support to Jax afterwards, having to fulfil her "promise".
Witnessing Jax easily approaching Pomni and spending time with her seemingly without effort is an obvious source of anxiety for her. Feeling guilty for what had happened before. Even with Kinger encouraging her to take things more easily, that relationships are a two-way-street and that "giving someone space should never be the same as giving up on them", she couldn't act on her own behalf yet.
If it wasn't for Pomni becoming more adaptable through interacting with others - this may never have changed.
Pomni's stance - and development:
As mentioned, Pomni wasn't susceptible to Ragatha's attempts to approach her. It actually wasn't until she found relatability and kinship in Gummigoo - that Pomni could see the other members of the circus as approachable. It wasn't until Kinger made her realize that "there is nothing worse than making someone feel unloved or unwanted" that she actually realized that her dismissiveness may have hurt Ragatha. It wasn't until Jax told her to let loose - that she could actually let herself be unhinged for a short amount of time.
Last but not least, it wasn't until her "fall-out" with Jax, the potential "loss" of a friend she had an easy time forming a "team" with, that Pomni bumped into Ragatha and mentioned to "talk after the show".
Most of their bonding afterwards happens off-screen - which may or may not make their intimate hug in episode 9 seem a little out of nowhere at first glance. But it kinda makes sense when watching their now-forming closeness as a direct response to both, their encouraging conversations with Kinger AND their guilt towards Jax. Because while Kinger's words may have influenced their perspectives, it's the lack of Jax' presence that helps them to find shelter and comfort in one another.
To go on a little tangent here: I mentioned Madoka Magica before and for good reason - in my opinion, every ship between the Holy Quintet can make sense under certain circumstances and especially in those universes where certain characters are "out of the way". For example, in a universe in which Mami has died/turned into a witch, there may be a possibility for Sayaka and Kyouko to get closer. In a universe in which Homura has died/turned into a witch, there may be a possibility for Madoka and Mami/Sayaka to get closer. For example, in a universe in which Sayaka has died/turned into a witch, there may be a possibility for Madoka/Mami and Kyouko to get closer. And so on. That's exactly what I mean by both "survivor's guilt" AND "pair the spares" tropes, it's not exactly a bad thing, but it makes certain other combinations way more likely to interact.
It's not 100% dependent on Jax' presence of course, but with his absence, Ragatha - who has continuously TRIED to get closer to Pomni - IS, besides Kinger, the Person Pomni WOULD try to get closer to. Because she may feel the same kinship in this situation with her as she felt with Gummigoo before. (This is sheer speculation, but Jax and Ragatha must have given "exes" vibes to Pomni, so she may have assumed Ragatha had known what it felt like to be ignored by him.)
After all, Pomni had made an effort to team up with Ragatha before - which was when Ragatha selflessly tried to save Kinger from Jax instead, sacrificing her own chance of having a moment with Pomni.
I was taken off guard by the "you have been my closest friend" line as well, considering how "out of sync" they appeared to be so often - but we've seen Pomni being adaptable to Gummigoo, Kinger and eventually Jax. All people she had felt a connection with, even if those had to "grow" first. So with the gentleness Ragatha offered her continuously - it's not even surprising Pomni could eventually grow comfortable with playing softball with her in the end.
Long story short and I hope that makes sense - it may seem a bit like they were a consolation price for one another, especially because they both, from their respective points of views, "failed" Jax. But with all these little moments they DID try to make an effort to take steps towards each other, the foundation is there. It may have been temporarily shaky, they may not see eye to eye on every level. But Ragatha's persistence to maintain her kindness paid off - and it eventually reached through to Pomni.
Pomni, who initially was in pain upon touching the glitched Ragatha - is now, after all this time, the one glitching, and getting touched in return by Ragatha. So if they continue to step towards one another - they can grow and heal together.