Boxwood near Azalea
I have an azalea planted 41 inches (trunk to trunk) from a English boxwood. I thought about moving the Azalea, but have found this too difficult. The azalea could be five years in the ground. The reason I thought about moving this plant is because the different Ph requirements of the ground for each of these plants. Currently the Ph, as read by a probe are 7 for each of these plants.
Montgomery County Maryland
The only way to accurately know what your soil pH is to have it tested by a soil lab. We recommend doing this every few years. Here is our page on soil testing with all the information you would need, including a list of regional labs who can complete the analysis for you: https://extension.umd.edu/hgic/soils/soil-testing
That said, you are right. azaleas tend to like a more acid soil than boxwood, which like things best at around 6.5 -7 pH.
Your azalea looks pretty stressed, especially if it is an evergreen type.
You can either remove it, or try making it happy by giving it a granular fertilizer for acid-loving plants like Holly Tone or a bit of ammonium sulfate in the early spring.
Here is a page from our website on Boxwood: https://extension.umd.edu/hgic/boxwood-culture-and-diseases-including-boxwood-blight