Link for mock orange (P. lewsii). https://www.google.com/search?biw=1920&bih=909&tbm=isch&q=philadelphus+lewisii+leaf&sa=X&ved=0ahUKEwjJ_vLT9eHPAhVMSiYKHfTCA00QhyYIHQ#imgrc=uTKiCH4f7siK7M%3A

There are several opposite leaves woody plants with similar looking leaves and lax growing habit. Sorry, I don’t know for certain what genus yours is. I could only suggest you should check out some of woody plants in e.g. honey suckle, wild mock orange (Philadelphus lewisii) etc… and see if you find a match? Link below with honeysuckle species grow in different counties of MI. Click on the species names for images. Best wish! http://michiganflora.net/genus.aspx?id=Lonicera