Girls Dont Really Know.
This is a fact for almost all of them. Girls, not women i mean. They still are trying to discover themselves. So are guys, but guys do it on their own. Girls sometimes project onto guys and try to discover themselves by how the guy makes them feel. "I feel truly myself when he is around".
Also at the teen years to 21 stage, girls are rapped up in this fairy tale romantic stage. Guys dont really go through too much of that. They try to "play the game" but they care so much more about just being with her then what they do when they are. This means that often the girl only wants all the happiness, romance and gestures not realizing that the most important thing is for your boyfriend to be there for you.
Think about it. Girls get mad when their boyfriend doesnt act to romantic. Even going from friend to boyfriend is next to impossible with most girls if you dont do something romantic to show you care. Its not enough for you to just be there for them.
Also girls dont really know what they want so they try to get everything out of their boyfriend. Take this example. You and some girl are at a bar or a club or at school. She looks over at two guys. She sees the kind, not so hot guy, confident with a sensitive soul. She claims aloud that he is her type. She looks at the other guy who is hot but a little shallow. Who she claims is not her type. The next day you ask who she hooked up with. Its not the confident, sensitive, guy. No. Instead its the hot arragant shallow one. She chose him because she wants to bring out the other guys traits in this one so she can have it all.
In short most girls at this age dont know what they want, want it all, or are still trapped in their little fantasy reality that they wanted since they were six that they can now experience and blind themselves to what they need in addition to romance. The problem is that true love is more than just about the first stages of romance. That is why most girls dump the guy when he stops being so romantic as they go on later in a relationship. As you progress in love there is less romance, more commitment and intimacy. But most girls see this as the "spark" is missing. That spark of romance is all they care about at that stage. Until they discover what is important down the road of love they dont really know what they want until THEY GROW UP EMOTIONALLY.
But the ones who have need this:
Being there for them through the good and the bad
You to stand by their side
You making an effort in romance to never let the flame die down to much later on.
For you NOT to be jealous