How can i take situation as?

​I am very worried regarding this since months and the things I am observing are not usual. To those who believe they are oversmart or have caught a spammer/weirdo, please stay away. My account is only a few hours old because I don't want to post this from my main account since my friends know about that. To those who know anything genuinely about such situations, then please share. ​The thing is, I am a little worried about the scenario going on at my elder sister’s sasural (in-laws' house). She has been married there for around 9-10 years. She has a younger devar (brother-in-law) who was in an affair lately and ran out of his house as the girl was from a lower caste. His parents didn’t accept them, but he chose the girl over his parents and house. Eventually, after 2 years, he got divorced and has now moved back home. ​But I have observed that since he is back, my sister does not visit us that frequently. Moreover, she didn’t attend the wedding of one of my cousins, whereas my jiju attends all functions and visits frequently. She remains at her sasural most of the time. She was once a jolly kind of woman, but now she has turned into a very mature person and rarely wears anything other than a saree. ​Moreover, in a few days, there is a wedding in her sasural of one of her cousin devars. We were having a conversation about that, and when I asked her about her real devar's wedding jokingly, she told me to mind my own business and not to interfere in her family matters.