I'm still disappointed Alison did not go to the beach with the gang

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That's a fair concern. We're told, repeatedly, that Allison was a part of the gang in highschool, but we've seen very little interaction between her and the rest of the group (Jeremy aside). She briefly came to the first gathering at The Fortress, but left quickly so we didn't see much of how she gets along with the rest. Her going to the club with Ian and Emma didn't result in the two girls talking to each other.
She's talked about Perry a couple of times, attempting to bait negativity out of Ian concerning him, but she herself hasn't interacted with him much. At Shine, with Cherry and Perry, the two are only on screen together long enough for Allison to say she'll go and get a round of drinks and then the rest of the scene is with either Ian or Jeremy. She also barely acknowledges that Perry has come to the club with her and Emma.
The second scene at The Fortress she sticks around a little longer, but again there isn't really a back and forth between her and the rest of the group outside of her interrupting, asking about, Perry to talk to Ian about herself. She's always just kind of there, around them, but doesn't interact with them. It makes her feel like more of an outsider than Cindy, Lena, or Holly who are all newer members to the social circle than Allison.
It would be nice to see Allison join in on a more casual social gathering like playing cards, going to the beach, having a shopping trip, etc. with some of the other cast members. Heck, Allison barely interacts with Cherry and they're supposed to be coworkers and potentially even friends. At least Cherry has the excuse of the bad past with Lena to keep her away from the group settings. It is disappointing, because I do genuinely enjoy Allison's love route with Ian and it's weird that they're into each other but they're isolated from the rest of the group.
They don't even need to keep their relationship secret like Ian and Cindy, as Allison has been pretty open about breaking up with Milo, before the story starts, and Ian and Jeremy can confirm he tried to attack them in jealousy. I don't think anyone would be upset at their pairing like Perry and Wade would about Ian and Cindy.
i want to see Alison and Lena in the same place in a path where Ian is with both of them and Alison incite Ian to cheat on her cuz we know deep down Alison hate her gut.
I don't think Allison hates Lena at all. I think she is jealous of Lena, as are most of the other women from the Scooby Gang, and sees her as a rival for Ian's attention, as do most of the other women from the Scooby Gang. I can see Cindy, on a loving Ian or regretting Wade route, becoming friends with Lena now that she has a better understanding of the modeling world and can relate more to Lena's struggles with Axel and how the two of them are perceived for just their beauty, but not their other merits. Perhaps Allison will get a similar treatment later if she ever interacts with the group.