Rune is busy guys; she's busy with reclaiming her identity from Garlemald, being a better gunbreaker and summoner, figuring out why everyone else wants to bang dragons, etc. No time for romance right now! It's low on her priority list!
So I think the thing with Shionne is two fold; one, she sorta knows on some level that it's okay, that things are different, she doesn't necessarily HAVE to kill off her thorns and possibly herself in order to find acceptance and companionship.
But two she... Still has to sort through THAT SCENE and the lingering effects it had on her. I think she's still dealing with that undercurrent of "what happens if the rules change again, what if it happens AGAIN" and I don't think she's quite ready to face that possibility.
And my view is that Shionne probably needs a swift, effective reminder that she can't just stay at arm's length at people, thinking that'll keep everyone from getting hurt, when... It's sorta already hurting herself and other people. And that if she keeps to herself like this, it's going to feel even worse if she almost loses people,
ETA: And I'm stealing the romance questions meme too!
and possibly herselfin order to find acceptance and companionship.