If you're an IRyStocrat, let me remind you:
IRyS has said that it's perfectly okay to member other girls. Hell, it's okay to hang out with those other girls, too. You may even end up watching those girls over her sometimes. But as long as you're thinking of her, she's okay with that.
Maybe even more than that. She's probably okay with you watching Mori right now, that much is obvious. She'd even be okay with you membering her. She'd be okay with you hanging out with her in member's streams, and even going to hang out afterwards at the special T4 hangout meetups.
She'd be okay with you staying later than everybody else and talking up the girl. She'd probably even encourage you to bring Mori home with you to keep hanging out after that. But of course, you're always thinking of her to make it okay, so you'd be inviting IRyS over, too, of course.
She'd love to hang out with you guys as a group and keep talking the night away, drinking down and getting a bit loose. She'd be fine as the laughter and jokes turn to lighter chuckles and flirts. When it turns from flirting to getting handsy, she'd be okay with that, too.
Even as things kept getting more heated, and you start putting your hands on her waist and pulling Mori closer, you wouldn't see her get upset. She may even join in, and help her out of her clothes as you all start to get really hot and bothered. She'd be fine with you picking Mori up and teasing her as you went to the bed; her following closely behind, of course, lightly pecking at Mori's lips to keep her in the mood the whole time.
She wouldn't even be mad as you dropped Mori on the bed and got to work. The foreplay would get more wild, and she'd be fine, even helping out. She'd probably even help spread Mori's legs for you when the time comes to move from foreplay to the deed itself.
But keep in mind, of course, that as you're plowing into Mori, and pulling her hips up as you hit her in the deepest places and grind against her most sensitive spots, that you DO need to keep IRyS in your mind for all this to be okay. After all, it's only okay if you're thinking of her. So even as Mori starts coming to a climax, you have to be sure that you're kissing IRyS, who'd be right behind you at this point, arms hanging around your neck and breasts pressing up against your back, leaning her head on your shoulder as you plunge into her dear friend, whispering how much she loves you and nibbling your ear while you send shot after shot of your love into the idol spread out on your bedspread, as she gets sent into a climax of her own.
And after all of that, with Mori sprawled out on the bed in a state of exhaustion from overstimulation, and IRyS still begging for you to keep leaning your head back and kissing her, it'll all be okay, as long as you promise to listen to her:
>"don't forget that you'll be with me next, okay~?"
