The DOF is too narrow to me. I would prefer the aperture to be stopped down to f16 for more detail. Your focusing point seems to be on the foreground (bottom of pic) rather than the heart. If your main subject in your pic is the heart, I feel it should be in focus instead of the foreground. Perhaps you could have stopped down your aperture to f16 and preset your depth of field (if possible with your lens) but this probably would have blurred your pics if you handhold. Use of tripod (if possible) might have improved your picture quality.
Personally, I would prefer the pic without vignetting. You purposely blackened the bottom of the pic? I thought the addition of the spore flag in the pic might be interesting. Perhaps you can PS it and see. But I love the dramatic sky colours. They bring romantic mood to the pic.
Keep shooting and posting!