How do you know?

How do you know your boyfriend wants to break up with you? What are red flags?
I threatened breaking up last night, cried and he kept saying no we aren't breaking up, I'm not leaving, I love you. So I talked to him about how he's been ignoring me and making me feel invisible whether he realises he's doing it or not and instead of fixing the problem he continues to ignore me and not fight for our love. Like he's the sweetest guy in the world but recently it just feels like he's too lazy to be bothered being in a relationship and we've talked about it so many times and he said things will change but they haven't. I just don't know what to do. I feel like my heart is going to burst any moment and I can't deal with that feeling.