Married man sending me signals?

i do kung fu and my instructor has been giving me signals that hes interested for a while. At first i knew him to be single, then i heard he was involved with another girl that goes to kung fu. Later they got engaged and now they are married. He still sends me signals and flirts and he always has a longing look in his eyes. I dont know what to do to push him away without him penalizing me in cl. i am testing for black sash this year. Oh and he always overdoes the PDA with his wife when i am around. What do i do? I do have a crush on him but i know its just a crush.... i am friends with his wife and have no intention to destroy their marriage. She loves him more than she loves herself and talks about him all the time. what do i do? most ppl i know say he doesnt really love her and only married cuz hes nearing 30 and his mother is bothering him to be married....i have only honourable intentions and wud not want to destroy my friendship with his wife and me