1. I agree with the above poster that there needs to be more light on his face. A reflector to your right would have helped.
2. Nicely done. Looks like you might have been able to push the focus distance a teensy bit backward to avoid getting so much of his leg in focus, but that's nit-picking.
3. I have two big problems with this one - the lighting on the subjects is quite flat, and it's really obvious to me that you tried to fix the overexposed sky, which is grey now instead of white. Also, as another poster pointed out, it looks like you removed some stuff from behind her head, but the cloning work is a bit sloppy and has an unfinished look to it. Also, this could be my imagination, but it looks like the color temperature of the couple is different than the background... looks almost cut and paste.
4. Cropped too tight for my taste. Is there something that you're trying to say with this composition that couldn't also be said without cutting off her elbow and the top of his head?
5. The heart shape with the hands is kinda cheesy if you ask me, but some people like that stuff.

There's something about this shot that looks off to me and I can't put my finger on it... I think it's just a general lack of contrast from the lighting being a bit flat again. It bothers me that there seems to be some nice warm light on the fence behind them (in the lower right of the photo), implying some sunlight from high behind them and to the left, but it doesn't look like you tried to use that to light the subjects at all, and instead overpowered them with what seems to be a large softbox to the left of the camera. I can see
hints of the warm natural light, mostly on her bum and lower back, but otherwise I think you missed a good opportunity to mix in some really good quality natural light.
6. I like.