Hey guys, it's In$tinct.
Keeping your girl happy is quite a task. You have to remain challenging and at the same time show your love to her. You need to excell in reading her and communicating with her. You have to make sure things are not getting boring for her both emotionally and sexually. I'd like this topic to be a container for what you do to keep the spark in the relationship.
Personally I have this little trick as far as sexuallity goes. I can make my girlfriend live her wildest fantasies. When we're in bed I tell her to tell me her most crazy, perverted fantasy in embarassing details and then when she's finished we get kinky. I start rubbing her pussy and slowly, passionately whispering her fantasy back into her ears. It got me several raging orgasms. It's also quite likely that she's never had this experience before. Fantasies are really strong weapons to use. As I think most of you know the female orgasm is ~ 90% cerebral. Use them to your advantage, be creative with them, and things will never ever get boring in bed.
If I want to stimulate her body intensively then fingering her and sucking on her clit simultanously works wonders. It can make several girls squirt too so be careful with your surroundings when doing that
For the emotional part I'm quite the romantic type. Not a needy little fuck, but I definitely like to surprise my girlfriend with sweet things. Real women appreciate it. Whores can gtfo or ride my dick when I'm single.
My girls always know that I will protect them. Most of them even told me that they felt so safe around me and that this was what really got them hooked.
And then again there's the protection money

Service is not for free. I'll often make my girlfriend do favours for me. Not necessarily big ones, but certainly things that will make her get up her pretty ass and do something. And then I reward her.
It is important that she feels like a woman besides you. You protect her, and she supports you. You PROVIDE protection but EXPECT support. If one of these are missing or done wrong the relationship will end in a train wreck.
Lastly, just a thought about communication. If they do something I don't like I don't get all cocky and pumped up. I don't even tell them that: "this bothers me because..." not gonna work with a woman. You need to tell her "this made me feel this way..." She will understand 1000000% better. And since she's a good girlfriend and wants to make me happy she will stop doing that. Or not... in which case it depends a whole lot on the exact situation what I'll do.
Let us hear what your ideas are and what are your little tricks you do and behaviours you take up to keep your relationships happy. Seeing all the newbie mistakes in this section, I do think, that this will be a helpful topic.
Peace,
In$tinct