Feeling shit :(

Recently my boyfriend has seemed different with me and I’m not sure why, he’s just so ‘off’ and takes longer to reply, doesn’t wanna meet me as much, he never used to go to parties and now all of a sudden he chooses to go rather than being with me, I just don’t know what to do , I’ve tried talking to him about how I feel but he just says ‘nothings changed’ or I love you, or stop worrying. I just have a gut feeling that he’s just not the same anymore and has gone off me