Sister in law

Hi everyone!

Just wanted to mini rant/ some advice on how to go about this situation.

My BF and I have been together 4 years, his older brother and his GF 6 months longer than us. They recently got engaged.

My family has always had a close relationship with in laws, so I wanted the same. Last year she was away for the year so I sent her gifts on birthdays/Christmas (expensive ones) and never heard from her. I planned a family weekend (their mom, boys and us) planned a boys and a girls day for us, and she bailed an hour and half into our girls day to hang it with friends... she didn’t tell her fiancé.

Idk what to do anymore, I’m at the point where I don’t even want to be around her. She doesn’t engage in conversation and when she does it’s only ever about her or the wedding. I’ve put interest into her life but have never felt it back