Quick critique, per req:
1. The rock wall creates a bit a dividing line; not fatal, but not ideal IMO. I would also like to see her hands posed differently; as-is, it appears that she has none, simply upper arms which disappear into the grass.
2. While not quite as cliche as a brick wall, a tree comes close. The main issue here is the fact that you've bisected her arm. If you must crop limbs, do it boldly, and never at/near/through a joint, and NEVER along the limb. In this case there's a couple of bright spots just above what I assume is a gravel path; while nicely defocused, this could easily be made to disappear with a careful application of the clone tool.
3. I'm rarely a fan fo flare (purely a personal thing; I understand it's popular right now) and to me, the falre here is just annoying; not strong enough to be artistic, but too strong to ignore. The line cutting through his head is a bit of a distraction. On the up side, excellent job of controlling light here.
4. There is almost never a time when it's good to pose someone square to the camera (referred to as "football shoulders") unless they are a football player, and never, ever a female. Again, your tight composition has resulted in a laterally bisected upper arm. Another good job of light control!
5. Pretty much exactly as per #4.
Overall, these aren't bad at all and I've seen people pay money for far inferior products. That said, while you're doing a good job of controlling ambient light, almost every one of these could have been improved with some strobed light. Do NOT get caught up in the mindset that using a flash is 'hard' or that using only ambient light makes you a more 'pure' photographer. The fact is that once you get over the initial learning hump with strobed light, life becomes much, much easier (also more expensive, but that's another story!). Photography is all about control of light, and try as I might, after 30+ years, I've yet to find a rheostat to let me adjust the sun, but strobes? They have controls built right in!