I noticed that something seemed a bit "off" between them in Greece as well. I put it down to the stress, fatigue and sadness of the event.
I have always seen them as close, devoted and visibly in love until recently. I really hope all is well. It would be so disappointing to see things fall apart after 5 children and such a long marriage.
There was some weird body language between them during the funeral. First, there was the way MC walked around Pavlos, rather than greeting him when she arrived at the cathedral with Queen Anne-Marie. I'd give her the benefit of the doubt that she was trying to avoid drawing attention away from the queen or her husband, but Pavlos seemed surprised that she didn't greet him.
Later during the ceremony, Queen Anne-Marie reached out for her son's hand and said something to him. MC saw it and grabbed his other hand. He immediately shook loose from both of them.
No idea what it meant, but it was odd. So hard to tell when people are under stress.