The character monologue at the end was moving, but I think that better pacing could bring it from good to great.
In my opinion, splitting up the description with dialogue snippets took away from your intended message. I was trying to figure out how the beginning information from the dialogue related to the incomplete description of the anomaly, expecting some sort of twist or big reveal. Instead, it was just a simple teleportation/timetravel machine. I personally think you could've delivered more coherent character development if you got all the situational exposition out of the way before exploring Bartleman's backstory.
Speaking of characters, Neer and Mulvaney seem to be inconsequential side characters that very subtly hint at Bartleman's trauma in passing. A dedicated section focusing on character interaction could build up the angst and reveal the true depth of Bartleman's grief, which would make the ending a lot more powerful.
Bartleman's dead father and disappeared friend also don't get enough attention. Their emotional impact on Richard seems secondary to Katherine's suicide, which is a sufficiently compelling reason for grief on its own, so you could just omit the father/friend detail.
LORDXVNV mentioned fridging, and I likewise felt that the wife's underdeveloped character made it feel like a cheap plot device. Ideally, I would like more insight into her character than offhand mentions of her liking space, eating yucky potato slop, and caring about her husband's safety.
If you gave her character more points to connect with, it would make it easier to understand Bartleman's grief, and you could leverage that relatability to further draw focus to "how the people left behind react." In other words, giving the reader a stronger attachment to Katherine would allow for more empathy over sympathy.
Overall, I see what you're going for and I like the message, I just didn't find the execution very compelling.
Novote from me!