Have had chickens here for 11 years. No idea how many chickens have come and gone in that time. Three weeks ago, if you had asked me, I would have said we've lost maybe half a dozen or so to predation, mostly to raccoons, one or two to coyotes, snd perhaps two to hawks. We processed several and had a lot just die of old age. But my faithful little Sheltie is getting old and is spending her days in the house instead of on patrol, and while our birds were out free-ranging a week or so ago, a coyote stole my good BJG rooster and four or five of my hens. So we're not free-ranging any more. It's our biggest loss ever. We've not had illness; we keep a closed flock. We did lose one hen to a prolapsed vent; we culled her.
I would say to you and your girl friend that there is a fairly steep learning curve when you first start keeping chickens. We all make mistakes, and our mistakes tend to be costly in terms of chickens' lives. But we try to learn quickly from our mistakes and correct them as quickly as possible. The rewards are worth the effort.
There is such joy is keeping chickens. It took me a while to figure out what it is, but this is it for me: chickens are a bridge between wild and domestic animals. They aren't dogs or cats, they are BIRDS. Yet they feed at my feet, which cardinals and blue jays won't do. I love hearing them purr and cluck and cackle contentedly to one another and, yes, to me. It's such a homey sound. Hang in there, don't get discouraged. You'll do okay!