The European Royals Message Board: New QVD and a question

A new QVD was born

Chloe Prinzessin von Sachsen-Coburg und Gotha was born to Daniel Pr. von Saxe-Coburg-Gotha and his wife Eileen.

http://eurohistoryjournal.blogspot.com/2020/04/the-newest-qvd-little-saxe-coburg-and.html

The text mentions that Daniel's father's marriage was considered morganatic.

My question is why ?

The last equal marriage from a male member of the SXG family was the brief (1942-46) marriage of Pr. Friederich-Josias to Grafin Victoria of Solms-Baruth .

Pr. Andreas married a commoner and so did his son Hubertus.

Why was Pr. Adrian's (pr. Andreas brother's brother and Pr.Daniel's father) wedding considered morganatic ?
Mere lack of consent from the head of the family ? Direct opposition ?

Thanks in advance.