First photo: The crop is awkward. Look up ‘Rule of Thirds’. She is too low in the frame and your perspective is probably also a little too low to make it work. The big yellow spot (a lamp?) is distracting. Be sure to keep an eye out for distracting background elements while composing your shot. You can either compose the shot differently to get that lamp out of frame or if you really still want that perspective you can remove the yellow spot entirely later in post. Be very mindful about where you crop body parts. In general, cropping at ANY joint is a no-no. The reason being is that it gives the appearance of being amputated. Its distracting.
Then of course from a technical standpoint, the whole image is soft and slightly dark. I’m guessing it was late afternoon and in the shade, so you weren’t likely to get any decent shutter speeds. Did you shoot this hand held? Consider using a support device of some sort for these really low perspectives, like a mini-tripod, bean bag, etc.
Otherwise, your color accuracy seems fine and the subjects expression is pleasant, although not a very flattering angle. Some photographers prefer to give their subjects a head angle that won’t cram the iris so far into the corner of the eye-socket; gives the iris a little more breathing room.
Second Photo: In general it looks more like a snap-shot of two people in mid-conversation. Doesn’t feel like a portrait to me for that reason alone. Again, be mindful of the position of your subjects so that you don’t find yourself cropping body parts in awkward places. Seeing the top of the girls knee and a tiny bit of the sleeve cuff is distracting to me. Her position in the frame is too low which contributed to her being cropped awkwardly. Perhaps you could have also had your male subject sitting on the ground like her, or elevate her a little to get her closer to his height. Also consider the shoulder orientation of your female subject: 1) shoulders square to the camera is usually not a flattering position for a female in a simple portrait. She looks much more broad shouldered than is proportionate to her head and she even looks more broad shouldered than the male subject. That should never happen. Also, consider how it effects the dynamic of the relationship between her and him.
Otherwise, again, you colors look nice, albeit the image is very soft. Definitely use a lens hood if you aren’t already, or if you are, consider using someone/thing to block some light for you.
Third Photo: Again, looks like a snap-shot of two people paying attention to something else, even a frame-grab of a video. A bit of a green color cast. The quality of light is nice, although I feel the image as a whole is slightly dark. Soft, too. For men, having the camera-forward shoulder higher than the rear shoulder is somewhat of a feminine stance. Men generally look more masculine with the forward shoulder a little bit lower than the rear, (and without squaring the shoulders to the camera of course, speaking in general).
Compositionally, at this point, if you just learn about and practice the Rule of Thirds, and then learn more about posing, you’ll be off to a great start compared to a lot of inexperienced shooters.