mmmh...I had noticed that too but I think they're very close friends!
Being a Queen obsessed ,I can tell you that almost the same thing happened between Freddie Mercury (I'M NOT TRYING TO COMPARE MIKA TO FREDDIE,NOT AGAIN!) and Brian May but Bri has always been married or engaged so... it's only because they have a good chemistry,as you said before. at least,this is my opinion.