My sister is ignoring me.

As a first-time user and a non-native English speaker, I apologize if my message is a bit scattered. I (F30) feel like my sister (F41) has been ghosting me, and I'm unsure why or how to address it. A bit of background: we didn’t have the most stable upbringing. She was like a second mother to me, and during my teenage years, we became best friends. She was my safe haven. Now, we’re both in relationships and have children around the same age, who are very close and love each other. Although we live two hours apart and have busy lives, we always made an effort to get together. Each time we met felt like no time had passed, and we had a great bond for over five years. However, two years ago, my sister started responding less frequently to my texts and calls. I initially thought she was just busy, so I tried to give her space while occasionally reaching out. Unfortunately, I rarely got a response. I tried to find a healthy balance—enough contact to show I care, but not so much that I’d be bothering her. Early on, she mentioned that her mental health wasn’t great, and I tried to help her find better support. She also came out to me, and for about three weeks, we communicated daily. I wanted to offer her a safe space if she needed one. She seemed to be improving, but then she just stopped responding altogether. It’s not just me; she has also ghosted our mom, brother, and my partner. I can understand her distancing from our mom due to their past, and our brother isn’t very involved in our lives, but I’m at a loss for why she has shut us out. When I suggested going no contact, she declined, and she’s never told us to stop reaching out or explained her absence. I’ve had to stop myself from overthinking the reasons behind it. I’ve tried reaching out for the sake of our kids, as it breaks my heart to see my daughter upset about missing her cousins. I miss them too. This past year, I’ve been dealing with health issues, including multiple surgeries and hospital stays, which I kept her updated on, but she hasn’t acknowledged any of it. That hurt because she was someone I trusted to be there for me. It’s been hard to come to terms with this situation. I’m sad because it feels like she doesn’t miss us, but I don’t want our kids to suffer because of it. We love and miss her family, and I’m unsure if they even know what’s happening. In the last two months, I’ve received a few short voice messages from her and her kids for holidays and birthdays, but when I attempt to engage in conversation, she ignores me. Recently, I reached out to her partner about the kids, taking a cue from my mom, who managed to connect with her this way. However, when I sent him a Christmas video, he replied that “your sister will send something from us.” I’m starting to wonder if he still wants to be in contact with me. I don’t want to bring this up on Christmas Day, but I’d appreciate any advice on how to foster a situation where my daughter and her cousins can stay connected.