The lighting is "flat". There is a lack of contrast. I think the lighting on the subjects faces is fine, not quite a skin tone, but not washed out either. You might try Hue/Saturation in editing which would help redden the brick.
Here is a note to composition. Is seeing the building so clearly in the background important? If it is in focus we will look at it, but do really want us to be looking away from the main subject which is the couple? If it is not important, crop it down as much as possible, and darkening it will help us spend less time looking at it. People tend to look at bright objects. more than at dark ones. In fact when I first looked at the photo it only filled my screen to the edge of the woman's extended foot. I did not miss out on seeing that uninteresting wall.
In general, be very careful of backgrounds. Notice how the woman's head is cutting into the window behind. Moving the camera slightly to the side would have left the solid wall behind her and the whole window adding a bit of depth.
Do you use photoshop CS5? I know a quick way to darken the whole image and then restore light where you want it.