Lighting. I'm a light fanatic. outdoors, indoors, I use strobes & speedlights.
Current lighting in your outdoor shot is even = there's no difference b/n you guys, your foreground, or background.
What would make it more
professional is lighting. for example your settings were 1/100, ƒ/5 ISO200. Shooting the same with flash at 1/160 or 1/200 of a second - you'll underexpose the background by 2/3 to a full stop, you will be lit up by the flash (two would be better, but one will do) thus you'll stand out. If the flash is on camera - to give it more of an equal spread and not concentrated beam in the middle You might have to move the camera further back and zoom in tighter.
Don't want to take my word for it - fine

Look at any television show/movies where they show photographers or videographers shooting ANYTHING - they all use softboxes, umbrellas, other light modifiers to create lighting and to isolate the subject from the background and foreground using both lights and DoF. Next time you'll watch a movie, look into person's eyes and you'll see catch lights. this is something you and I don't have at our homes if were to sit over a cup of tea

but it is done to PUNCTUATE a subject.
Now, you got 6 munchkins over there and getting them all to sit while you set things up isn't easy or practical (when at work, and bride is one of 10kids, my umbrellas are up already, thus it is a different scenario). So in PP you can through a graduated filter just to darken the background a drop and have you guys stand out
