<human>: Can you summarize the given text in a few sentences?

So like the title says I've been with my girlfriend for two years now, and I do love her. However, recently I've been talking a lot with a coworker of mine who seems to be a really nice companion and is someone I'd be interested in being with.

One thing making this so difficult on me is that my current girlfriend has Cystic Fibrosis, a genetic lung disease that as of now is considered a terminal illness. I love my girlfriend, but lately I feel our relationship has become boring and stale, and we've been arguing a lot more often. She is originally from Guatemala and she only lives with family in the U.S because the medical care she receives is far better here. Her birth mother and a lot of her friends still live there.

I feel like I should end things with her before things progress any further with the other girl I'm talking to (to save her any further pain) but I can't think of a way to go about it without destroying her. She's been having a rough time lately medically, and the last thing I want is for her condition to get worse because of me.
<bot>: GF of two years has Cystic Fibrosis. I'm interested in someone else but don't know how to tell my GF without feeling like I'm destroying her.