If you get into a fight or an argument....never leave the house. stay mad as hell if you want to, but don't ever be the one that leaves. (even if it is for an hour....don't leave) You are giving up "leadership potential" if you do. And ladies...like it or not, you want the man to be a leader.
if your girlfriend has male friends, tell her they are not allowed in your home if you are not there. Doesn't matter if the guy stars in the TV show "Queer Eye For The Straight Guy" (if you get my meaning)....it is a bad practice, and you too should never be home alone with a female friend or a female friend of hers. If she wants male friends....tell her to go to the Post Office.
don't ever let her think you are lazy. be neat, clean, and keep things in their place at all times. it doesn't take much effort.
make decisions on things together. for example: if you paint a bathroom, or if you do (against the wise suggestions of others on this board) buy something together...run it by one another.
know that she is not your mother. don't expect her to mother you.
i think the "date night" thing is overrated. i mean...it isn't like you two have been married for 10 years and have 3 little kids. i think it is more important to have one night where you don't have the TV on. Spend that night talking....about anything. (if that makes it a date...so be it.)
be honest with things about her that rub you the wrong way. if she has a habit of not putting hair care products away in the bathroom....tell her. don't let the little things bust you up....but don't let them fester either.
do you have offstreet parking? if so and there is only one spot,....you do know that that spot belongs to her right? In the winter...you have to be the one to sling the shovel....not her.
OK...now what you don't want to hear:
Be a man. Make a committment.....Marry her.
Too many people use the excuse that they want to live together because they want to make sure things are "right". That is a bunch of crap. If she wasn't the right one, you wouldn't be living with her either. You will have differences with anyone you marry. differecnes are good. if everyone was the same it would be boring. Husbands and Wives give up on their marriages way too easily because of offences against one another....and having said that:
Here is the best tip i can give you. This is what my pastor told me before i got married. Think of the worst offense your girlfriend could ever commit against you,....and forgive her for it now...before it ever happens. That offense may never come....but you need to know in advance that you have it within you to forgive. If you can't,... end it now, and move on.