It's not a bad piece at all. It has a very nice color scheme with the orange tones and cool highlights. There's some asymmetry compared to the reference, but it's not a huge deal. If you aren't already in the habit of flipping your canvas horizontally now and then, give it a try; it makes it easier to see asymmetry.
As for suggestions for improvement, here's a paintover. I did this hastily, so don't take it as gospel. Think of it as suggestions for changes you COULD make, if you think it looks better. I'll talk about the significant changes I made and why.
Firstly, that reference is a difficult one to use for lighting. It's an indoor environment with multiple artifical light sources (obvious due to the multiple cast shadows on her neck), and it looks like you condensed it down to 1 yellowish direct light source and 1 blue-ish ambient light source, which is a good idea, but it's best to pick references with the exact lighting scheme you have in mind when you are inexperienced and non-confident with painting.
I thought the main thing that could be improved was his collar. I'd expect to see a cast shadow from his head and occlusion shadows where it meets his neck. I may have over-done it, but I thought it made the picture read better.
His pecs are too exaggerated for this lighting, and the chest anatomy is not as realistic as the face and neck (I made it even funkier though). You just need to find a good ref to get it right. Male high jumpers or swimmers might have the appropriate level of muscularity you're looking for. Or Iggy Pop.
There is little value difference between the lit areas and shadowed areas, which is appropriate if there's a strong ambient light, but I ended up making the neck shadow just a LITTLE darker to make it read better.
I added cast shadows from his hair. You don't have to put in EVERY single cast shadow that would logically appear, nor do you have to make them as big as they would be in real life; but if they will improve the 3D illusion, add them.
I hope that helped. Let me know if you have any questions.