Make a new focal point in your images to simulate depth of field
Make a duplicate of the Background layer by dragging it onto the Create a New Layer button. Now go to the Filter menu and down to Blur>Gaussian Blur. This filter is used to create depth of field.
Set the Radius slider in the filter’s menu to 25px creating blurring across the entire image. Now hit OK.
Add a layer mask to the top layer, then press Cmd/Ctrl+I to invert the mask to black. Use the Eraser tool set to black, 50% Hardness and 20% Opacity, and paint over background areas. Work towards the foreground to gradually build the effect.