The subjects look happy in their pose and you did not a nice job to avoid blowing out the details in the whites. For my taste, I generally try to minimize the flashed subject/dark background look which can hard to avoid in this situation, I would normally use a wider aperture to blur some the background details. I would also try to keep some of the limited ambient light by using a slower shutter speed (manual mode on my camera but maybe night scene mode would work). I would then need to check if I revealed too much distracting background because sometimes, dark background is best to conceal the clutter, etc.
