It's a big adjustment when you make the leap in your relationship to cohabitation. Just because you're a love match doesn't mean you are a design match. Check out Apartment Therapy's tips for decorating with your significant other.
Beware of compromising so much you wind up with a decorating style that both of you hate. Rather than making no one happy, try taking turns on choosing items. That way both of you will get things you love and you may wind up with stronger decor because it will look collected rather than forced.
Each of you should get one or two "vetos", no questions asked. However, be sure to think carefully before you use your veto, because both of you get one.
Search for design inspiration together. That way you can spend time together and enjoy looking for things that get you excited about decorating your place. Vintage shopping, art museums and even design blogs are all great places to look for inspiration.
It's okay to wait until later to make some decisions. Moving in together is a big adjustment and if you find yourselves fighting about furniture all the time, it may be better to leave the topic for now. Once things have settled down, design disagreements may naturally disappear.
At the end of the day, what matters is that person you love that you chose to move in with, NOT the stuff that both of you brought to the table. The most important part of your home is the people, not the belongings, and be sure to focus on that when you want to throw his ballcap collection out the window.