How do I[28M] make people feel better and less like they are "walking on eggshells" around me?

See question. I'm tired of hurting people. In the end I just hurt myself.

I've been told that my gf[28F] feels like she's "walking on eggshells" around me. Please help. What does this mean? I don't want to upset and hurt her anymore but it seems like we can't even have simple disagreements anymore. Everything is horrible and turns into a very bad fight

What can I do to make people stop "walking on eggshells"?