I feel like people tend to not fully recognise just how momentous a step the cottage truly is and I know that sounds categorically insane because of how obsessed we all are with the cottage but bear with me.
Prior to the cottage Shane and Ilya have literally only ever spent time together one-on-one when they happen to be in the same place and, even then, usually only for long enough to hook up. We can theorise about potential nights where they went multiple rounds and spent time together in between but there's not much evidence in canon for that. The only times they have ever really spent time together alone outside of meeting their immediate physical need for one another are 1) very briefly on the rooftop, 2) in Boston (and we all know how that ended) 3) in the hospital - and two of those instances can only really be counted in minutes.
Now they’re looking at a trip, booked in advance, with the express purpose of spending time together and not just a night or a day or two. Two whole weeks. If you’ve seen that post that calculates how often Shane and Ilya likely met up throughout the years you’ll know we’re looking at maybe 20 times total, throughout the years. If we assume they spent a total of two hours together each time (which I believe to be an overestimate, especially with the early years) that’s a total of 40 hours, spread out over 7 years of hooking up. And now they have two weeks. That’s over eight times the amount of hours they have spent together up until now, combined.
And, of course, as the viewer we already know they love each other. We’ve been screaming at our television screens for several episodes now, begging them to be open and honest with each other. Pleading with them to actually talk to one another. We are so beyond ready for the cottage by the time it arrives and, because we are aware of TV tropes, we are pretty sure the season will end with Shane and Ilya resolving their issues and coming together. It feels like a foregone conclusion to the viewer but to them, as people, it Absolutely Isn’t.
We, the audience, know that they are already in love by the time the cottage comes around. They know that they’re already in love by the time the cottage comes around (although they may not know that the other person is too). What they don’t know is whether they actually function together outside of their crazy sexual compatibility. They don’t know if they actually make sense in the quiet moments. Whether silences will be comfortable. Whether the air will feel heavy between them. They don’t know the shape of each other in everyday life and they don’t know how they fit around each other. This is also why the “I like you” scene is so important, because that truly was an unanswered question before the cottage. Yes, they love each other but do they actually enjoy each others' company?
In that context, Ilya coming to the cottage isn’t just a huge step, it’s a fucking leap into the abyss.
And I know that I'm preaching to the choir. I know we've seen the posts about how nervous they must have been, how brave they both were to follow through on that plan and finally give themselves room to figure themselves out, but it was literally an insane level of commitment from two people who have spent years running from their feelings. It bears repeating; the cottage was monumental and that cannot be overstated.