are we getting a Halloween update this year and also you've been teasing us with the 3some for how long? Are you ever actually gonna add it?
To my awareness there are no clear announcements on the next update. However, the last public Patreon announcement (from 16th October) shows the new pool location: https://www.patreon.com/posts/pool-time-9110159
So my guess would be that the next update involves the pool in some way. But that's just speculation at this point.
Regarding your title question: The developer has stated multiple times that this is to come at some point in the future, but for now they're still expanding on the "getting caught" theme for all 3 female characters.
Halloween themed content hasn't been confirmed anywhere yet. But I'd very much like to see that as well.