To improve this line, change the abstract word to a concrete image. One way to achieve this is to think of an object or a scene that evokes feelings of happiness to represent the happy feeling. Describing the smile shows the reader something about happiness, rather than simply coming right out and naming the emotion. Also, the symbolism of the tomato further reinforces the happy feelings. OK, the image has gotten embarrassingly obvious now, but you can see how the introduction of the tomato permits us to make many additional connections.
Poetry always has a theme.
Theme is not just a topic, but an idea with an opinion. This is not a theme. It is only a subject. It is just an event. This is a theme.