I feel like a shitty girlfriend

My boyfriend is constantly asking me to tell him why I love him and In all honesty I always lie and say I'll do it later to make other excuses but it's simply bc I don't have any reasons why I love him. I use to have a million and could tell him whenever. But he's changed and keeps saying he hasn't, but it's true. He's a asshole all the time, always is brutally honest and doesn't care if he hurts my feelings, he actually upsets me a lot but idk.