Losing a best friend

Right so I need some life advice right now. I have known best friend for around 10 years now, and like most relationships we have had our ups and downs, but we have never really had an argument. Lets call my best friend Sophie. For a good while now on and off I have felt like we are becoming more distant. We both have our own work lives, but we always try and meet each other after work. We also have Luke who is also our best friend. He comes back home during his time at Uni and we hang out and stuff. Lately when we me and Sophie do get to hang out, she has been telling me how much Luke has been driving her insane, with constant messaging, whining and basically being immature. This has gotten so bad that its now all we talk about, and weirdly whenever me and Sophie try to meet up he'll message out of the blue to get us to hang out there and then. Whereas me and Sophie have planned this time together in advanced. We dont really like it when he tells us to drop everything there and then to go and see him, because we've made plans, but it also makes us feel guilty. It ruins the time we have together. The thing is Luke rarely messages me, he will always go straight to Sophie. Both me and Luke are closer to Sophie then we are to each other. And I can appreciate that because they have known each other since childhood. I would rather Sophie and Luke have some quality time together as well, so we all have this equal bond with each other, if that makes sense. However I do feel like Lukes behaviour towards us has started to cause a wedge between me and Sophie. His texting has gotten so bad with her that she has had to turn her phone off, which then causes her to ignore me as well. What has also gotten me down is the comments Sophie makes. I cant remember them word for word, but I know she said something about getting fed up with talking to people and that its too much effort. Now she has also started to ignore my messages more and more over the months. When I was thinking about, I was like...hang on. I realised then that it was mostly me having to start a conversation, or even suggest going out. Which is where I am now. Last week we was having a first proper conversation, when it suddenly stopped. I didn't hear anything back for days. Except on our group chat where she did message. This isnt the first time she has been like this over the years. Normally I'm able to talk about it. But now Im actually scared to, I don't know why. But confronting her is giving me to major anxiety. Her doing this has just really pissed me off and I thought you know what, no. I can't always be the one fixing it. The reason why I mentioned Luke was because I know its not just me she does it to. It's childish but now whenever she messages on the group chat I just ignore her now. I guess my hope is that she'll see that something isn't right and message me if everything is ok. Luke also did this the other day (Although i'm not sure why), and she asked why everyone was ignoring her. I felt really bad, but its also what I wanted her to experience what we had to experience. I don't know what to do. We are all going for a night out in a few days, and I know they'll make some sly comments towards me throughout the night. Or there will be some bitter words exchanged somewhere. But I'm still so mad at her, I dont even think ill be able to speak to her and its all just gonna be awkward. If anything was to happen, it would basically be Luke and Sophie hating against me because thats just how it runs. Or she'll get really drunk and make a big joke about it like it doesn't even matter. Is this person really my best friend? am I just having false hope? I havent been able to sleep properly, i'm angry, crying....even more angry. I need Oprah

Thanks guys, I've managed to patch it up with them. We've been out of high school for years now, I guess its just another dynamic change happening. Its easy to forget everyones got things going on with their lives. But we are lucky that we are still friends now and if not in the future then we have had some great memories.