I know others have answered this for you, but I don't think they've done it justice.
To say, "Envy from the Pink Rose" isn't anywhere near enough of an answer.
If you're saying you don't know who Nicole is, it means you didn't chat with this woman on Swyper (twice), meet up with her at MacAllen's Bar and make out with her on your birthday, then go home to her place with Sandy and fuck both of their brains out in arguably the best threesome in the game so far. I know you didn't do this, because if you did, you would not be here asking, "Who the fuck is Nicole"!
No, you are most definitely not the only one!
The game straddles a number of genres, and depending on your taste, you may find it spot on, or you may find it unconvincing.
Ever watched Scooby-Doo? It usually involves a fun but somewhat serious mystery which the gang solves and explains at the end. The clues are there and it's fun to guess them. At the same time, you have Scoobs and Shaggy doing some insanely stupid shit that usually plays out for the best by the end, and they often eat more than their body weights combined in hot dogs, hamburgers or who knows what.
That's kinda how you need to interpret some of the scenes in this game. Some are serious, some are crazy. Does a toothbrush really make a loud pop when you pull it out of your ass? I don't want to know, but I laughed. Can a student throw a can of soda at a teacher and run away taunting her? Not in the real world. Does it matter? No. Is it fun. Yes. Can you dig it? That's down to you.
The only time I can remember her telling him off was very mild (on Rooster):
Jill: "Did you just flag Fuckface's post as harassment?"
Tybalt: "No, that wasn't me. What do you say to my proposal?"
Jill: "It's my cluck. I can see that it was you. Please, be nice to people I care about."
I'm pretty sure Tybalt is smitten with Jill. His goofy efforts to get her attention, and the things like him getting caught in the background of Jill's Rooster post perving on her when she's sunbathing. He wasn't doing that for prestigious reasons...
Think about it, a buxom babe is staying in your dorm and you see her on a regular basis, you'd start to enjoy meeting up with her. Look at all the people here smitten with her just from playing this game! If she put out, and didn't look hideous from time-to-time, even more players would be on team Jill. 
I don't think Lily fucks with Quinn the way Quinn fucks with others.
Quinn enjoys making people feel uncomfortable for the sake of it.
Lily was just calling Quinn out on things she deserved to be called out on.
I've said it before, but the HOTs would benefit from a person like Lily in a position of authority; she cares for the girls well-being, just like she does at the Pink Rose.
Unless you go around sticking your finger up her ass (I know it's tempting), she's a sweet girl.
Yes, I played a total pussy run once (skipped through a lot of dialogue though), just kept the mc's head down and studied hard. He saw less tail than Magnar!
Lots of people are commenting on what's going on with Jill's expression.
She does look a little pissed, but I would be pretty annoyed if it's another scene with her and Tybalt and she's fallen in the water and she's removing her clothes to get them dry.
My take is that it's a look of determination. She's got a plan for the mc and she means to see it through, she's decided to take the relationship to the next level, and this romantic spot by the river is just the right location to set the mood. Oh shit, was that a pig I just saw flying overhead?
Yep, can totally see that happening.
Tybalt tries to paint it like it's all Trent's fault and he (Tybalt) is doing his best to help Jill out and all (we obviously know it's bullshit but Jill falls for it). But the final words in the conversation are 100% blackmail:
Tybalt: "Well, I can make sure we drop all of it. For you."
Tybalt: "No lawsuits, no police reports, no nothing..."
Tybalt: "And, in return, maybe you could do a few things that are right, for me?"
Jill: "Yes, of course. What are they?"
Jill you big-boobed, dumb bitch!
