I dont know. That seems to be a custom on the political scene. They also kiss female head of states.
Trudeau with Merkel:
Obama with Merkel:
Trump with Merkel:
But Trudeau is a little creepier than all the other head of states. He and Merkel had a candlelight dinner together. I have never seen her doing this with other leaders:
I read somewhere Merkel vomited after kissing that Mommies Boy Trudeau, can you blame her? ..
Merkel was concerned Trudeau might try to accost her at dinner she knows he has a penchant for older German women, and that's why she brought a "guest" with her for dinner ..