I hope you don't mind my giving critique as if you had lots of experience doing these 
1-flash lit portions are flat--get your flash off camera (if it wasn't) and place it more off to the side. Given the orientation of the woman's face, I'd have placed it camera right.
2-good color in the background. You perhaps could have pulled the ambient down a bit more (increase f-stop, lower ISO or increase shutterspeed if possible) to pull in some more color. The angle doesn't help the shot, in my opinion. I don't like how her dark outfit is blending into the darkness of the bridge behind her. Try to show shapes. Also--this doesn't really read as a silhouette shot, so you really needed to pop MORE off-camera flash in there (it looks like some on-board flash was used ?) to bring out the faces.
3-For me this shot only really works if you've oriented the subjects so that their silhouette creates clear (mostly) distinct shapes. Here the silhouette is mostly a blob of dark--we can tell what it is, but it's just not as emotionally evocative as it could be. In order to do this, you sometimes have to tell the couple to make the plane of their faces more coplanar (ie. so you can see the shapes of their features). Have them lean in and shoot continuously as they get closer to the kiss. Sometimes the shots just prior to touching are the best.
4-Not a fan of the framing, but at least the tilt seems to have a purpose here: 'righting' the woman, placing focus on her, where it should be. This shot is begging to have had some off-camera flash in there.
5-fine, though I'd have liked it a bit better with their heads having some clearance around them--meaning, no buildings or other objects surrounding them.
I just noticed the second silhouette shot in the second batch. THAT'S the shot. Nicely done. The framing could have been improved a little (the lower half of the image awkwardly leads to a cut-off pair of legs). But the shot is a really powerful one nonetheless.