Why is he avoiding us?

Ok, so I have this little trio, two girls, one boy. We are very open with each other, we love each other like siblings, but for the past week, the guy has been ignoring us, like we don't exist! It's making me and her feel horrible. Her and I tried to slowly bring the subject to him, but I guess he knew that and left. He doesn't hardly answer our texts either! Please help me! I am so frustrated with him!