Your composition is pretty good (Two-Thirds is one of my favorite techniques) and there's a nice contrast between the pink-red of the roses and green of the background, and you've made the subject pop as a result of having the background blurred. However, I'm wondering if the roses would have more impact if the background were grey, or even muted. You could potentially play around with some symbolism if you used the grey. Then again, I really like the colors and their vibrancy, which gives the picture a sense of life.
Overall, I would say that this is a successful photograph. The composition and complimentary colors draw my eyes right to the roses, which, in turn, brings my eyes to rest on the heart in the glass, emphasizing the title and point of your picture.