Do you think something is wong with my boyfriend?

has the weirdest relationship with his sister, he said when she got married he cried at her wedding cause he tought he was losing his sister...(odd) and he has pictures of her in his room and when we're arguing he's always like i swear on my sisters life that im being honest and im like wtf dude your so weird! and he says that shes really important to him... do you guys think this is weird cause id do im not close to my bros like that.. i mean i chill and have a few beers with them but i definetly wont cry at the weddings