There's nothing wrong with being emotionally open with a girl you are in a serious relationship with. You can't keep your guard up forever and keep playing it cool or the lack of affection will drive her away.
You can be madly in love with a girl, but it doesn't mean you should allow yourself to be taken for granted. A lot of girls will try to exert a little power over you from time to time, even the best of them. It's just female nature!
Just don't allow it! The answer is that simple.
If a girl asks you to run errands for her, act jokingly outraged and tell her "no, I'm not your slave" or say "sure, if you give me $5". If she gets angry, starts sulking or tries to guilt trip you, back away and act a little cold with her, as though her sulky behaviour is unnattractive and offputting. If she asks what's wrong, tell her "I don't find you attractive when you're sulking".
A lot of guys fear saying no to their girlfriends and cave into her when she sulks because they think their girlfriend holds the power and will end the relationship. It's actually quite the opposite. When you give into her sulks, she knows she can manipulate you and will soon start to lose respect for you. Just condition her to fear sulking and guilt tripping you by subtly letting her know how unnattractive it is.
Don't go so far that you refuse to do anything for her. By all means, be a gentleman, if she's struggling with heavy bags lend her a hand, for example, but do it on your OWN terms, not when she demands it!
My girlfriend and I are very emotionally open and constantly tell each other we love each other etc, but she knows I am not and never will be her lapdog.
