Theme is very important in writing. It helps convey a main idea, and gives substance to a story. Without a theme a story would just be a bunch of random words that hardly have a point. For example in the story of the tortoise and the hare, the theme of the story is that slow and steady wins the race. Without that lesson the story would just be two animals running through the forest. The theme of a story doesn't have to be blatantly obvious though, it can be very well hidden within the story. A story also can have multiple themes, you might have to search harder for multiple themes, but that could also lead to better understanding of what you are reading. The same thing goes for ideas being present in writing. Without ideas there pretty much wouldn't be a story in the first place.
I believe the theme I am going to try to incorporate into my play is the idea that love is patient, and worth waiting for. A theme such as this is important to me for various reasons. One of those reasons is because I am a hopeless romantic, and I fantasize about various scenarios, so I have plenty of ideas. It also is important because the type of story I would write is how I wish things could be in my own life. It is funny though, because most guys don't do the things I fantasize about. Thus making it a fantasy I guess. I also greatly enjoy romance.
In the play the main conflict would be the struggle of a girl who has her heart broken, but still is deeply in love with the guy who broke it. When she finds out he has a new girl she makes it her mission to break them up. In doing so she winds up meeting another guy, and falling for him. In the end her ex realizes that he still loves her, and the girl must make a choice between her past, and her present. This may sound really corny, but I like it.