How do you know when your boyfriend loses interest in you?

😔I feel like my boyfriend lost interest in me. He’s acting different around me he wasn’t like this. Today was our 4 months together and all he did today was make me feel like shit. He told me he didn’t loved me as much as I do. He also told me he hates that I’m clingy and that he’s going to stop everything that makes me feel clingy. He didn’t even wanted to hang out after school today when I was so excited to have a picnic date with him at the park. 😞😔he wasn’t like this to me. After he told me I was really special to him and that he loved me a lot and that he had deep feelings for me. He starts acting different towards me he also told me he doubts. We’re going to last 😞after we both lost our virginity to each other. After he was my first everything. Why did out of all sudden he started acting cold and indifferent towards me. Why ?? 😞I thought he loved me. I haven’t done anything to him. After I gave him my virginity, my time, everything and he pays me like this.