Jealous, yes, but not over a guy. I refused to play those games as a teenager. If I smelled competition, then I simply moved on. But! I do have a related story you might enjoy, and feel free to store it for future writing (since this is a good example of young female relationship woes): Shortly after I joined the Army and made it through Basic Training and moved on to AIT (Advanced Individual Training, i.e. occupational training), there was another female soldier (I was 20 and she was probably 19, so we were young) who would stick herself in between me and any guy I so much as looked twice at. If I remember correctly, she successfully "stole" three different guys I was friendly with (NOT THAT KIND OF FRIENDLY). She was much more sexually aggressive than I, so she always ended up with the guy. (Not that I move really slowly, but I wasn't looking for quickie relationships, so her pacing beat mine). And, as mentioned before, I will step aside the moment I feel I have to fight for a guy. I'm sure on some level this other female thought she had won some kind of competition. I laughed then and I laugh now at how obvious her meddling was. Her last meddling resulted in a permanent relationship, though, so she left me alone after that.
That's different than Kara's situation, obviously, who rightfully has more invested in Adan emotionally, but you've made her into such a wonderfully sympathetic character that I don't want to see her kicked around too much. Even better, have Adan put a huge foot down, draw a very thick line in front of, etc, Sumire's brazen advances (like you mentioned, she won't show up again for a while, anyway). You're right; they're teenagers, so Adan's still figuring all of this out. I'd think by the time Sumire might reappear he'd be able to give a manly-man "NO" to Sumire rather than veiled suggestions: "There's a nice kingdom... waaaaaaay over there..."
"I don't go to very many social events apart from fires." - carlsojos