Here's a Business Insider article from msn.com about the 13-1/2 hour overnight train between Bucharest and Chisinau. Read it and be grateful you weren't along for the ride. I must say that it doesn't sound very different from the couchette experience I had between Rome and Sicily in 2015, except for the lack of border controls. The loading of my Italian passenger car onto a ferry was a good stand-in for switching out the wheels between Romania and Moldova.
The distance between the two cities by road is about 270 miles. The train doesn't take quite as direct a route, swinging north to Iasi, thus the especially long ride.