I think I understand what you are going for here. Possibly the heart just stands out too much. If I may make a suggestion I would possibly try the following to "tone it down" a bit. Create a mask (selection in Photoshop) of your heart and then delete the current heart. Make a copy of your background and delete all of it except what is under the mask. Now lighten or increase the brightness on the heart until it is almost washed out. Finally, adjust the transparency of the heart until it blends well and appears to be a halo or cloud effect above the mountain. Just a suggestion because I really think this image is done well.
--Sarah