Honestly, someone should just me a fanfiction of this premise or better yet, just make a fanfiction where Daru dies, the party collapses, the FL tries and fails to get Est back to her party and Est just moves on from Athena all together. In my mind, this is a better character arc for Est then to be petty towards a girl who is, to be blunt, not really a good leader let alone a love interest.Why does the author just embrace that instead, i mean look at Overlord.
I think one of the reasons why this fails so hard is because the author wants a main character, this story i see it as trying to be a deconstruction of the trope... but doing that is far too difficult and so easy to mess up, it would have been better instead as a slice of life with the main arc being that the relationship is broken because of what they did and how they interact in a place where they have to look at each other every other day
... Or make it a thriller about an old adventurer that after loosing his friends he breaks down until he finds a girl that looks like his old girlfriend/spouse/wife/etc... so he makes it so that he is introduced to the party and using his experience he finally kicks the one man stopping him from reviving the old days, just to have him survive the cave and become powerful enough to be dangerous, so now he is desperately trying to create as much a gap between them as possible, but slowly the newest member of the party realizes that something is wrong and tries to uncover what that is while avoiding both the suspicion of the rest of the party and the one that got kicked since she see him as possibly vengeful, but in reality he is also trying to find clues of the wrong doings.
Sorry for the many and long posts... i´m sick and i have nothing else to do
After all in any team, everyone needs to watch everyone backs not just then frontliners. If anyone gets hurt/killed then that's on the leader's fault for not protecting them nor making the necessity precautions to prevent this stuff from happening. Now kicking Est would have been fine IF we saw that him getting hurt is a constant thing that been happening too much before his exile, that would've been understandable, but from what we the audience seen, and from what i heard from previous comments in earlier chapters about the light novel, this only happened once. If that all it that's to kick someone out of a party, then I wonder how this party even hopes to last in a long run without Daru power holding them. I'm aware that there are more factors on why this happened but at this point, they don't justify that actions done before the exile happened.