There's a popular saying, "Action speaks louder than words", but really, which is important?
In the normal circumstances, when you say you will do something but you don't do it, someone will get offended or sad. For example, you promise your girlfriend you would try to change. After you say it, you don't do it. You keep putting it off to tomorrow and then tomorrow. Guess what, tomorrow never ends. There's always going to be a tomorrow after tomorrow. The next tomorrow can be the tomorrow you were saying. Please shape up and do it. Don't make excuses.
The other thing is the word "try". People don't realize it but it is actually a negative word. Why? Because if will absolve your responsibility by saying it. When you say "I try" you're neither saying you will nor you won't. Using the word "try" for your promises is convenient for you but it hurts your partner more. Use the word "I will". Doing something starts from your self determination to do it. Don't make promises you can't keep.
In scenario 2, you've been going out with your girlfriend, or rather, someone you say is your girlfriend for a while. You guys do all the stuff couples do. You hold hands and go out together. You make corny jokes and pamper one another. Both of you do all sorts of stuff together but you don't tell her you love her. You believe your action speaks louder than words. You believe what you do has already told her you're serious with her.
Well dude, a news flash just for you. IT DOESN'T. Your girl will always be lost in between the parts of confusion and insecurity. You would ask, why will she? Because she doesn't know for sure that you're serious about her. She can't officially tell people you're her boyfriend because she doesn't know for sure. She's afraid that you're going to turn around and leave all of a sudden and say that there really was nothing between you, that you were just "benefits without responsibilities" friends. It's not about trust. Trust is the only thing that keeps her from leaving you. IF you say you love her and you mean it, it will reassure her and your relationship bond will be stronger. There's really no reason you shouldn't say it. After all, she's with you because she's serious about you.
From both situations, i can conclude that BOTH word and action are equally important. After you say something and then you do it, it will give people the feeling that you're credible and believable. That you're a man of your words. Words and action goes hand in hand. One can't go without the other.
People are complicated and insecure creatures, and even more so in this time and age. Sometimes, clarification is needed. Other times, action from your behalf is necessary. You lose nothing by offering and it could be good for you and people around you. Think about it.