Wait a minute, in hentai land it's okay to get all handsy with your local hunters? Even without the intentions of having sex? And even make the exchange in/near the red light district? Again, without the intentions of having sex? Huh.
There's a lot up for interpretation here the way I see it. My assumption is that Liane had already sold her body in some way (yet her body was clean during sex, though it could have been for artistic purposes) and was simply saying goodbye to the costumers. If so then the ending monologue would be how Firis saw everything from her naive point of view, maybe sending a letter back to their parents or writing in her journal. It could also be possible that Liane indeed "only" had a "very good" relationship with her costumers and for some reason sold them stuff during night, and then used "her getting caught" as an excuse to sleep with Kald, alternatively didn't want Firis to know how flirty she had to be with the costumers in order to get continuous sales.
Kind of disappointed. It's nice and all but it seems really weird that she'd go for anyone other than Firis, that Firis wasn't somehow brought up every other sentence, or at the very least it wasn't all excused as doing it to protect her perfect adorable wonderful precious little Firis's purity. Liane always seemed about two seconds away from trying to have her way with her sister in the games.
@LRaglan Well, she pretty much says she's doing it in order to support Firis financially, even if she doesn't mention her directly. It's kinda like when she went away for hunting(?) before they left the mining village, it was out of necessity, and she was even going to great lengths to cover up how, thus keeping Firis' naive mind pure. The last page kinda shows that she's supporting Firis and successfully managed to keep it a secret from her (if she indeed was a call girl). But again, there's a lot anyone can read between the lines here, and I think it is deliberately not mentioned in order for you to interpret it as light or dark as you'd want at your leisure.