The three rules I have in a gay relationship (myself being in one that has lasted 6 years so far) is to:
1. Be considerate about their feelings. This goes for emotional, mental, physical. Sex obviously you WONT HAVE ANY FUN if they aren’t having any fun. Mentally and emotionally, not being considerate about their feelings or thoughts or what’s happening around them environmentally will just create fights, and fights don't help anything. It’s all about thinking about whether or not it’s going to hurt them or make them upset before you say anything.
Which leads me to my second rule, and the biggest rule of any relationship...
2. Communication. If you don't talk about your problems then nothing gets solved and those problems will only sit and stew over time and the relationship will fail... If you don’t let them know when they're being mean or inconsiderate, then they will never learn and the possibility of it happening again is high and stuff like that can build up and weigh you down... If something important comes up, something they may not necessarily enjoy hearing, you need the trust there in order to tell them and if you don’t have that trust then what do you have?
3. Have fun and keep things romantic. Make sure you guys have something you both enjoy to do, me and my boyfriend love camping, cars, baseball, movies, video games and eating out. Obviously if you guys like each other its cause you have common ground, so play on that and have a blast. Being romantic can mean any number of things, the broadest term however is just making sure that you do those little things that continue to make them feel like they’re important to you, buying them a flower every now and then, surprising them with a nice meal out, buy some wine and have a quiet night in, text them during the day to say you’re thinking about them (this one here has gotten me through some rough days).