If you don't have the room or desire for two separate chins, meaning separate cages, play times and everything, don't get a second one. Even if they do get along, which there is no guarantee they will, the new one still needs to be quarantined in another room for 30 days before intros can even be attempted. Also it can take a long time to introduce two chins, sometime they hit it off right away, other times it can take months, sometimes never, and sometimes they like each other for awhile but then decide later they don't.
If he seems fine he probably is, most chins sleep most of the day anyway so being alone for 7 hours isn't really a problem, especially if it in the middle of the day. At most get him a cuddle buddy (stuffed animal thing to cuddle), and try to spend more time at with him if you think he is lonely, some chins even like mirrors. A second chin could turn into twice as much time and work, so only get another one if you want another one. Contrary to recent things being said online and in pet stores chinchillas really don't need a companion, it's like saying humans need to live with another human. Chins do live in colonies in the wild, and are social creatures, but think about how much room they have to get away from each other in the wild, lol.