AIO for not wanting my eyes permanently on my bfs arm

Me and my bf have been together for 3 years and we are both 19! He seriously wants my eyes tattooed on him and he has been raving about it for almost a year. I feel mean for saying no and that I'm overreacting but am I?? I'm so stuck inbetween just letting him or sticking to plain no. Im also tempted to say yes because not bragging but my eyes are diffidently one of my favourite features since my ethnicity is kind of rare and I want to see it tattooed but this is more a commit thing for our relationship in my opinion.