I've never really thought of moving in with a significant other as a big deal. I mean, it is a big deal, but it's not as big of a deal as people make it out to be. I tend to think of moving in with someone as a logical step in a relationship, that logic being based primarily on a desire to create a life and a world together and, in a secondary sense, on practical and economic considerations. Those two elements, however, don't always conflate in such a way that makes moving in with someone appropriate. Actually, it's a very rare occurrence when desire and necessity match up. But when they do, it's wonderful.
But still, a lot of people treat moving in as a much more dramatic thing than it really is. It becomes romanticized or feared, like it will either cure all of your relationship woes, or completely break you down into some un-showered, constantly farting, sexless pair. Neither of these assumptions is correct. When you move in with your S.O., not that much changes. Hopefully you'll learn to be a more patient person, and your communication skills will grow, but other than all your things being mixed in together in a place that has both your names on the lease, not all that much actually changes. So if you've got some misplaced ideas about what it's like to actually move in with someone you're in a relationship with, here are some things you can rest assured will not change:
1. Your couple problems
The issues that exist between two people don't immediately disappear or escalate as the result of switching to co-habitation. Your issues are the same issues. Your past relationship doesn't immediately change because you live together. Everything you've been through is still everything you've been through. So be prepared to still have the same fights over whatever it is you fight about. The only difference in regards to fighting is that now you wont be able to storm out and go home because you already are home. The silver lining to this: What DOES change are your priorities regarding what you want to fight about (way fewer things), how you communicate (given that you can't run, you have to stay and talk), and the way you deal with conflict as a unit.
2. The amount of effort you put in
People often think that when you co-habit with your S.O., everything is all bodily functions, Netflix and falling asleep without having sex. Yes, this happens sometimes, but when you live with someone you still (or at least, you should) spend the same amount of time going on dates, fussing over sexy lingerie and throwing yourself into their arms when they walk in the door at the end of the day. The volume of romance doesn't change, you just might find that you're "doing nothing" together more often, which shouldn't affect the "doing something" part.
3. How much time you spend together
If you think you're going to see each other more when you move in together, be realistic: People's jobs, hobbies and other commitments don't immediately change as soon as you move in together. You'll still be spending the same amount of time together as you did before, especially if you used to stay together every night as well.
4. Your S.O.'s personality and habits
The person you're dating isn't going to suddenly change once you move in together. So this is the part where you have to be very certain about what you want, because the person you're about to live with isn't going to become someone else just because they live with you.
5. The things that annoy you about each other
Speaking of your significant other's personality, all the things that annoy you about them are just going to continue annoying you. You won't be cured of your annoyance upon sharing the same living space. If anything, those things will be exacerbated when you're constantly in close quarters. So you want to be sure you're really in this relationship unconditionally (and by "unconditionally" I don't mean "if they are bad to you." I just mean "if they bite their nails and leave them all over the couch".)
6. Your relationship anxieties
Unfortunately, moving in isn't going to cure your personal anxieties about your relationship either. And why would it? Only YOU can control how you feel about those. Even when you've moved in with someone, you're going to be constantly working to improve yourself, your relationship, and to learn about one another. But co-habitation isn't a band-aid for any of that. Becoming secure in your relationship (which is just about becoming secure with yourself) is about hard work more so than anything else.