Ok define city. Warwick and west Warwick are both in Kent and have comparable neighborhoods to providence? They both fall under providence's metro area so you could argue they're part of the city.

In general the areas to avoid would be the Olneyville/Manton/Atwells triangle. The areas around Charles, Douglas, branch, and lower part of Smith st. And the Lower south providence and Elmwood neighborhoods. Also the Upper cranston st area. Definitely avoid the areas around public housing. There are some nice parts of these especially in the Elmwood Lower south side so don't completely take them out of consideration. Olneyville is slowly being gentrified too.

The "good" areas are most of the east side, the west end, immediate dexter training ground areas and federal hill neighborhoods, upper Smith st along with the Elmhurst and Mt Pleasant neighborhoods along the north providence line. Silver lake and Washington park are ok.

I don't know what kind of crime filled city your gf thinks providence is but it's no where near comparable to parts of Philly, Bronx, Chicago, etc. No you won't get randomly stabbed, shot, kidnapped etc. Avoid problems and they'll avoid you. There's also crime hotspots even in the good neighborhoods, fox point iirc has the highest share of break-ins of all providence.

And since you work in the east side you should consider either Pawtucket and especially east providence. Easily take the Hendrickson bridge over and rent is alot cheaper too. EP as a whole is pretty nice