SPOILERS
I've only done the "Tiefling camp party" once, and with a 19CHA character. So I am *very* attractive... That said, if this isn't directly associated with my CHA (and even then...), these conversations are a bit awkward for a couple reasons.
1. It came out of nowhere. None of these companions had expressed any real interest in me prior to the party (none of the characters were above "medium" interest in me, most neutral). Now, admittedly, there are people who are like that. I think it fits Laezel's character perfectly. She doesn't really know how to express affection, so it would make sense that her wanting me came out of nowhere. Also it seems to fit Astarion as well. He's very forward, probably very sexually promiscuous, and that night he is drunk. But it doesn't really fit the other three. There should have been some build up. For example, to this point, my character knows literally nothing about Wyll because I've failed all conversation checks with trying to get him to open up. But now Wyll wants to bang me? Very weird.
2. I picked one to bang and the rest were all jealous without any instigation by me. This is sort of chaining off the "this came out of nowhere" point, but it was weird that after I picked one the game had the rest of them congratulate me on what I thought was a private conversation, and do so in a way that made it seem as if they wished it were them. Some came right and said they wished it were them. Again, I think Laezel's character insisting she would go bang Astarion instead of me fits her really well. It's just weird that all 5 of them wanted me this badly after I've made zero affectionate comments at any of them.
Based on the type of dialogue option you choose when talking to your companions, they will flirt with you. For example, when I was having a conversation with Shadowheart about killing each if we can't get the tadpole out of our head. I chose the option of tying her up until I can find a cure and after the conversation she responds with "Try not to think too much about tying me up." That was her flirting. Also, Gale shows he cares about your character especially after Nettie poisons you. Gale gets extremely pissed off, which shows me he cares. Astarion is always the biggest flirt. Lae'zel acts tough but dialogue options, you get the hint that she has come to care about your character. As, for Wyll he also shows and interest but I haven't spoken to him too much. Taking all this into consideration it does make sense for them to get jealous if you choose someone over them.
