My sister and her boyfriend have been dating for a while now. I recently hung out with them and noticed that he always is either holding her hand, has his arm around her, kissing her head and hand, is touching her somehow etc., and is constantly saying that he loves her. It seems really clingy and I know that with my previous boyfriends they never really did that. Is this normal? I feel like it’s unhealthy and I should say something but my sister seems to be okay with it I guess.