The trick to do a good photo-style background is to simulate depth of field
This one is especially hard because the background is not straightly behind the character, but the basic principle is to not only make things blurrier as they are further away from the camera (which you have indeed done very well), but also when they are further away from the focal point
Wow very well done background!
And the girl is very pretty!
I wish I could chat with you a lot like we used to