All I really have to tell you is that moving in together is a whole new ballgame. It isn't always bad, and even breakups can be amicable, because you get sick of each other at the same time. lol I don't see marriage as any different than moving in, except without marriage, you have more wiggle room to get out of it. I like to keep my options open. :D So, I think moving in is a nice "next step" for a serious relationship. I've lived with a few men, and what has come out of it for me is A) I will always own my own home, even if I move into his place, because it's proven to be a safety net when the guy gets sick of me and B) I will never rely on some dude to pay for me and wind up stuck in a dependent situation.
I think the biggest arguments and annoyances I've had with men are money and needing my alone time. I can't stand someone being around me 24x7. I need my space, so many times, I do get annoyed with someone who is hanging around alllll the time.
But, the biggest issue for me has always been money. Who will pay this and that, and who will pay when we go out. My divorce had a lot to do with money, because every time we did something, he wanted to negotiate who pays, and it got really old after a while. Going out went basically like this: Where are we going..and OK, I pay and he'll drive, or I drive and he pays and then if he pays I pay for the movies...yadda yadda. Too much money talk, and he thought I should basically carry the weight and do what he wanted me to do. I have little tolerance for such things.
I suggest you keep a security blanket in the form of a savings account. Lots of people say it's a negative attitude to have, but my savings account has been a security blanket for me on many occasions. When I got divorced, my ex up and left, which was fine, but that of course left me with all expenses. No problem...got my savings. Oh, and another thing. YOU DO NOT PUT HIS NAME ON IT!
I don't care what any idealistic person says: you don't go into a relationship with the idea that it will get nasty or fall apart, so there is nothing wrong with securing yourself. You don't expect him to cheat, become unhappy, leave, clean out the savings account, or just decide one day he wants to flake out. With a savings account, it's fine. He can do whatever he wants, and you'll be just fine. This is especially true if you have kids.
It's ok to be in love and want to move in together. My first move-in was with a guy with whom I was going over his house and staying at his parents. He would tell me to come over and just walk in and his parents were ok with it. I felt so weird, but he told me it's fine. Welll, one day his mom told me she was uncomfortable with it. He lied to me, so it was just weird and awkward after that. I should have known, but I was 18 and stupid.