While I can't disagree with you on this point, I can still say it was poorly handed. I just got to the end of the update with what is supposed to be a cliffhanger and my thoughts were "I don't really give a fuck about this to be honest". And the main reason is that there's almost no built tension around Gillian to make this moment feel like a big deal.The thing is, the game is already telling this exact story for Lena. So i can see how some people might not be all that enamored with suddenly getting more of the same. But then on the other hand this shoe was clearly going to drop from day one, so no one can really say they weren't given time to brace for it.
For example, if at some point Ian had already opened up a bit to Lena about his previously relationship and how it damaged him for a while, there would be something more for me to care about. If he also tried to put up a front saying he was now over it, that woud also add more tension to this, because now we would see that when he gets to see Gillian he's flustered. Now we know that when the next episode drops Lena will piece things together and see that something is off between what she's been told by Ian regarding his feelings for this girl and the actual true. Now we get to feel some anxiety from this moment while waiting to see how Ian will handle this moving forward. But we don't get much of that. Gillian as few references so far and her potential impact hasn't been built or developed properly. Plus, I already saw from Lena's side the story of the former relationship from which Ian had basicly no information. I already saw that shoe drop, now I'm just getting more of the same, but with least context. At least we got to know Axel before that, we saw him building tension with Lena, so when things started going down with them, it made things a lot more interesting because we were already invested in this storyline, which is not something I can say on Gillian's side.
The game so far made us little to zero invested in her and if we don't get that, the actual real way to make this more impactful was if never got see a picture of her and probably didn't even knew her name. Eva could very well have all Ian's circle refer to Gillian up until now as "she who's not to be named" and that simple fact would make this moment so much more impactful, because now it would leave us wondering who's this person that Ian just ran into. Obviously most of us would assume pretty quickly who she is, but still that very small lingering doubt is what actually could make this a nice cliffhanger and why it actually felt so underhelming for me and for a lot of other people.