I do get it, but I also think it's important to remember that Stella is an alien. The given age could be wildly different compared to humans. At least that's what I choose to believe to make it less weird.
The aspect of talking to Galna is simply a story created for the duplicate Sylvie made. Whatever the real Galna does is vastly more dangerous and not limited to something like talking.
No thanks. I've seen your other posts and someone who objectifies women like you is a bottom of the rung piece of garbage. I hope you realize how worthless you are before the next woman you use makes you regret it.
Regardless of the status of an ex-boyfriend or not, your obsession with whether she is a virgin or not is some high-tier cringe shit. It doesn't matter. Full stop. Nothing about the possibility of her having had sex with somebody else changes their relationship now.
Earlier chapters largely imply it to be something with her wings as we have never seen her spread them and she seems to have a complex about them when she is with the other girls talking about them.
The implication seems to be more like his memory got messed up following an incident, possibly shock as the doctor said, and he slowly remembers as he re-experiences things.
While I won't say it can't happen, this doesn't really feel like the kind of work to kill off any major characters. The tone of this series is very light-hearted with the occasional tension but you can't have major consequences like that without drastically changing the core appeal of it.