Heart break

Yesterday, my boyfriend broke up with me, and his "reasoning" was incredibly vague. He said "I don't think this relationship is going how it should be going and I don't see it getting any better and I think we should just go our separate ways." 
And then, today when we worked together, it was so confusing. At first, he tried to avoid me, and then I gave him the rest of his birthday gift (his birthday is the 19th). His gift was a couple boxes of Girl Scout cookies. After that, he acted the way he did before we started dating. 
It was so confusing and I hate this. I just want answers and I want to not be heartbroken.