My (29M) and my 19 year old sister have never been close until recently but we just formed this super emotional bond this year. All of our other family members are kind of annoying and fighting and it's just been us in what feels like our own little peaceful world lately. We hang out and she rests on my shoulder and I put my arm around hers. We text we each other affirmations, we text "I love you" throughout the day. It feels like I'm falling in love with her honestly. I don't know if she feels the same but I have a lot to lose by crossing any boundaries so I've just been enjoying what we have for now.