You shouldn't have to change for anyone, If it bothers you that much you should ask him to quit watching it... If he truly "loves" you then he'll do anything for you. Ask him about it but don't change yourself for anyone.
Hey.......I don't think you should be concerned if your boyfriend watches porn movies.This is absolutely normal. But as you mentioned you boyfriend is less interested in you then before...then I think you should try something , you might change your looks...hair style. you can make yourself more attractive by doing exercises...and yoga. I am sure you will feel a change in your boyfriend.
I think you should definitely ask him about it. You need to communicate, and if he's only interested in you for your looks, you need to find out asap.