Son married Dec 21, his spouse filed married filing separate. Can I still claim him as a dependant. He recently turned 18 and was under my care all year

My son was recently married (Dec 21, 2017) to his spouse who is in the military. I took care of him all year until he moved to another state to start his family in January.  Can I claim him on my taxes even though they were married before the end of the year?