When you become a huge fan of a new girl group and she gets jealous. 

Momo

Momo is the type to try to convince herself otherwise. She would shake

it off because she knows that she will always be your favourite idol. She

would slyly shut your monitor off when you were watching videos of your

new interest and sit on your lap, kiss you, anything to remind you that you were hers. 

She would learn the group's dance and dance it for you, giving it her own y and cool

twist making it even better than the orignal. She's possessive but she's confident about

the bond you guys have. 

Mina

Mina would feel insecure, not knowing what to do. When you would meet

up for dates, she'd become quiet, even quieter than usual. She would keep

her feelings to herself but would gradually increase her skinship with you

to give herself a sense of comfort and security. She'd let it pass (or not) and 

she would hope for the best every night before she went to bed, hugging 

the stuffed penguin by her pillow while thinking of you.

Sana

Sana wouldn't want anytime to pass before she took action. She would

want to diverge your attention from that 'stupid' girl group back to herself.

However, she would want to do it in the most subtle and seemingly sweetest

way possible. Candlelit dinners were definitely a must and she'd take you

out to the amusement park, winning prizes of bunnies and teddy bears for

you. Insecure, yes; but she would carefully devise a plan and stay

confident with it until she was sure you forgot about that girl group.

Dahyun

Dahyun would worry about it more than she worried about her swollen ankle or

the fact that her eyes were bruised every morning when she woke up. Dahyun is possessive

and protective, she didn't trust anyone to take care of you but herself so it hurt her that you

would do this. She knew it was completely dumb that she was jealous because there was no

way that you would pick them over her but love can drive poor Dahyun to do dumb things. 

After reassurance from you (accompanied by some giggling about how cutely jealous she

was), she would be able to move past it and question her sanity during the whole ordeal.

Chaeyoung

Upon discovering you were a big fan of them, Chaeyoung would become

really sad. "Chagiyaa.. Look at me.." She'd pout and bury her head into

your arms as she tried to stop you from watching the group's most recent

live performance. She wouldn't hesitate to let you know that she was jealous.

Her effortless aegyo and adorable puppy dog eyes would quickly convince

you to put the laptop away. This was just the kind of effect Son Chaeyoung 

had on you. 

Tzuyu

Tzuyu would laugh at the group, straight up. She'd say something along the

lines of, "They're cute but I'm way cuter". Tzuyu would be noticeably

more charming and ier when she was around you. It wasn't that

much about proving herself as better, she just wanted you to stop playing

their whiny, high-pitched song as soon as possible. The situation barely

has an effect on Tzuyu as she knows the strength of your relationship.

Jihyo

Jihyo really wouldn't mind whatsoever, after all she had some favourite girl groups

of her own. She would even offer to attend shows with you or to buy you the album

when you guys saw it while shopping around. She would occasionally jokingly say

things like "just don't forget about me" or "close your mouth, you're drooling" just 

to tease you while you were watching their videos. At award shows, she would attempt

to be friends with them to get them to hang out with you because she knew you were 

shy. 

Nayeon

Nayeon would stay quiet, not wanting to seem controlling or overly jealous.

A heart sunk in her chest when she discovered that you changed you ringtone

from 'Like Ooh Ahh' to the other group's newest track. She would have a

hard time sleeping but ultimately decided to leave the situation alone. Nayeon

wasn't insanely jealous she just wasn't quite fond of it. She would hold your 

hand tighter and hug you more possessively and she would eventually realize

how strong your relationship actually is.

Jungyeon

At first, Jungyeon would be a bit envious hearing you talk about the lead dancer's

beautiful brown eyes and alluring smile. The more you said, the more she was

enticed herself to check out this amazing group. Sooner or later, Jungyeon would

start to like the group as well, fangirling along with you. She would laugh at herself

about how she used to be jealous that you liked this group and when you ask her

what she's laughing at she will say 'this' and tickle attack you.