This only adds the ability to copy keys with momentary access to your keys. Anyone with sustained access to your keys can just take them down to the hardware store, so this doesn't really change the "spurned lovers" equation.
I don't see why the other people would want to break into my house if they weren't interested in stealing my things or hurting me (and if they are just breaking in to like, hang out in my house, that's a bit weird but not really something to lose any sleep over). If they do that habitually, I think they'd find breaking into the house without using a credit card to buy a copy of my key is quicker and less risky than using KeyMe. I am not particularly worried about the extremely rare threat model of being my non-criminal friend or coworker's first break-in, where they decide opportunistically to break into my house because I left my keys somewhere and they know they can easily make a copy of them at a kiosk.
I don't see why the other people would want to break into my house if they weren't interested in stealing my things or hurting me (and if they are just breaking in to like, hang out in my house, that's a bit weird but not really something to lose any sleep over). If they do that habitually, I think they'd find breaking into the house without using a credit card to buy a copy of my key is quicker and less risky than using KeyMe. I am not particularly worried about the extremely rare threat model of being my non-criminal friend or coworker's first break-in, where they decide opportunistically to break into my house because I left my keys somewhere and they know they can easily make a copy of them at a kiosk.