If the sister dumps you, definitely make a move on the sister.
First one is a little too red (I get that it's sunset, but still) and she looks a little tired.
First two and the last one, you have the obvious sunlight behind, which makes the light from camera right a little odd. Most people don't notice this, so maybe it's just 100% me, but I find light that I don't "believe" to be a bit off-putting, and I don't "believe" this light -- I know you're pushing light in from the darker side, somehow. You DID do a pretty good job pushing it in there, though, I think.
Lower hand position in the second one's a little odd.
#3 is wonderful in all ways. She's rocking the pose, the negative space on the left has the pier leading straight to her face. The light is more "believable" and on and on. I'm sure there's something wrong with it, but I'm damned it I can find it.
#4 has the slightly odd light, but after I look a little more I am willing to believe the reflector as if it were a bonfire or something, maybe. It's maybe not quite there, but I can imagine it. The girl's looking enigmatic, looking out of the frame with her back to the sun and, maybe, to the city. Feels like a movie still. She's got a very interesting face. Not "hot" at least not in this short, but very appealing and photographically interesting. She is also rocking a pose, but quite a different one. I get a pretty strong "don't talk to me, son" vibe.