Breakup blues or sign it could work?

I moved out and split up with my boyfriend of 3 years about a month ago. He’s been amazing and loving since I left (through the packing and move out stage and in some continuing text and communication).

I’m struggling to feel the same feelings that I did (of knowing the relationship was not what I wanted) when I made the decision to leave, and keep wondering if we could make it work. I know this is in part a reaction to the grief and loneliness I feel now that I live alone. How can I decipher whether this doubt of the breakup and feelings of reconsideration are a natural part of my process of grief or if it’s really worth taking a second look and trying to make the relationship work?
I appreciate any guidance you can offer to help me move forward either way.