1) It's a big adjustment, and you don't really know what to expect. Even if your s/o spends a whole week at your place, living together will be different. There are some things you just can't expect and won't find out until they happen, but hey it's all part of the experience!
2) The "Honeymoon phase" or not the Honeymoon phase... Not sure if it's jut me but I won't lie, I did kind of expect to have a "honeymoon phase" the first month we lived together. Well I guess I've watched too many chick flicks. Honestly, since we were already spending 3-4 nights together per week...not much changed, and I see it as a good thing actually.
3) Splitting the bills. Most importantly, having a discussion about finances and budgetting for the rent, bills, expenses, groceries...etc. (so #adult)
4) Double the mess. I was living alone for almost a year before he moved in, and especially the fact that he eats double what I do and cooks double what I do = double the mess. Well I guess it was also a good thing that I wasn't a neat freak, because I probably would have freaked out a bit. As I mention in this post, I suggest to just chill out, ESPECIALLY in the beginning transition period.
5) Double the fun. Living with your s/o = lots of laughs, fooling around, pranking, and joking. There literally just isn't a day where we don't laugh, and it's always great to have someone cheer you up after a bad day.
6) Becoming comfortable around each other. You get to see it all, and see your partner in all of their moods. I don't believe there is such a thing as being "too comfortable". I think if you're truly in love there is nothing that will "turn you off" or "disgust" you about them.
7) Talking about serious stuff. Everyone has different expectations on things such as responsibilities and chores. It's important that you express your expectations, but also remain willing to compromise. Overall, all responsibilities should be fairly equally distributed, but this also does not mean that you shouldn't enjoy doing a bit more for your partner once in a while.
8) You will fight about small insignificant things. Some days I'm just tired and I get a little pissed when my boyfriend leaves a dirty plate lying around, while other days that wouldn't bother me for a second. Living with someone will be very unpredictable, and you will fight over small things here and there. Important thing is to just view them as that: little things. Eventually you will just get used to it anyways, and those little things will stop bothering you.
9) You can still have time and space to yourself. I talk about this in this post. But when living together, even in a STUDIO (meaning no closed bedroom), I was still able to manage studying or watching my own tv shows...etc. It definitely was easier when we moved into a 1 bedroom apartment, and then in a house, but believe me when I also say that I miss us being in the loft. There was something really special about being able to speak and see each other no matter in what room we were.
10) You get to REALLY see whether your relationship has REAL potential. The main reason why I wanted to take the next step was because I wanted to really be assured that our relationship had the potential to be long term. I was afraid to date someone for 2-3 years, to then realize that we just can't live together. You definitely get to learn A LOT about your partner, and your relationship dynamics. I think that it's worth trying for all couples who have been together for over a year.
11) You always have someone to do things with you when no one else does. Pretty straight forward and always fun, even when your partner couldn't care less LOL.
12) It's normal that there are days when you, or your s/o is too tired for sex. It happens, and no need to overthink it or start thinking that you're already acting like an old couple. Just be mindful of other "causes" as well, such as stress for example, and always let your partner know that you care and you're there to listen.
13) You will have to make an effort to keep the romance and excitement going. The reality of it is that you see each other every day, and probably more often in sweats than when you were living separately. It may require more of an effort for some, but just break the routine once in a while to spice things up. It doesn't take a lot, and it will probably remind you of some great memories of your early days together ;)