Okay, so I think there might be a missing variable flag in Episode 2, because unless I'm being dumb then it is impossible to get the positive reaction to the kiss on the lips in Episode 3 when you're watching the movie with Claire. So in order to even get the option for that kiss, "varExpressed_love_ep2" needs to be True. However, this only gets set to True if you meet with Michelle in Ep.2 and then talk to Claire about it. And if you go meet Michelle, that means you don't have the conversation with Claire and the opportunity to creep on her while she's napping, which means it's impossible to get the 9+ lust required for the positive reaction to the kiss.
In ep2.rpy line 1908 there's a bit of dialogue that gets triggered "if varExpressed_love_ep2 == False and varSis_love > 10" where Claire says she loves you and you say it back, and then if you choose the "Hold her" option you get some points. I'm guessing this is where "varExpressed_love_ep2" should be getting flipped to True, but isn't.