Des anyone think that Mark has stronger feelings for Callie being और just best friends?

Ugh..No,not really.
आप can see that he loves Lexie. Callie&Mark are just friends,best friends.It looks like after sex that they had,when AZ was in Africa,all Mallie प्रशंसकों started to think they're in love.Sex doesn't mean that suddenly he loves her या that she loves him.