Do you really understand though?
I have a theory: She has only ever had sex once.
It wasn't a pleasent experience, it was filmed, and is being used to blackmail her. Can you blame her for being a little traumatic over sex and not wanting to rush into anything, even with someone she's always seen as a friend, trusts to help her (not immediately fuck her) and only recently started looking at differently?
I personally think she is terrified of intimicy.
After this update I don' think they need to really need to tell one another they like each other anymore. To me it's apparent they know they like one another , considering how often they are kissing they are feeling more like a couple to me. As well Erynn is starting to be more bold when it comes to the MC and less hesitant and awkward. I could be wrong but that is my personal interpretation of their relationship after this update.
Completely agree with everything, i'll just say, it definitely feels like we are closer now, she's opening up...
Some events may happen to help her cross the threshold:
First the obvious, finally resolving the Ethan business, no need for further explanation, he goes to jail, she's free from him.
A possible meeting with Zane(it may happen in the next beach event that is planned since Zane=Surfer dude), i can foresse an awkward meeting since they had a sudden break up and haven't talked (much) since and it probably gives us the opportunity to say "she's with me" to up the "commitment level", i'm sure she will appreciate some jealousy and disdain lol.
Last but not least, some Melissa teasing and pushing for it, she's been pushing for this relationship since episode 1, Erynn didn't even know the MC was back in town yet and Melissa was already trying to make it happen... Now that she knows they've been at it, because Emily blabbed... i can see her pushing even harder for it.
do we know it was in a public place though I don't recall that ever being mentioned at all. Unless I forgot something. So im going under the assumption it's unknown if it was public or not. As far I know it could of been in the safety of her or Zane's home and it's possible Zane and Ethan planned to blackmail her so they made plans to record her even in a private space.
It would be an interesting thing to learn how Ethan got the tape... many possibilities here, did he "loan" the place they fucked? Did he convince Zane it would be cool to tape it(and share)? Zane shared because he's a dick and wanted to brag? Hopefully we do learn the whole process.
On a different topic, how dumb is Santiago? Provided you won the race it gets announced in the speakers "lane 3, 'MC' Moreno" and he didn't put 2 and 2 together lol.