I'm scared he wants to break up

honeeyyyyy

My boyfriend and I have been together for 3 1/2 months and recently he hasn't been replying as fast as he used to and our conversations haven't been very interesting. He told me that we need to have a serious talk about our relationship I asked him what about it but he hasn't responded yet. I'm totally in love with him but scared he'll break up with me. What do I do? I can't handle a heartbreak.