Loss can be difficult to deal with for some, no doubt.
I know people who have expressed a deep-seated fear of losing someone, not through death, just the loss of friendship or relationship...but when those very same people do it to others, just simply disappear...it's ok? Umm, nope, it's not ok. But that's people for you, they have a way of being disgusting assholes.
No, it's not right what they do.... so they were not sincere. Better to stay away from these fake people.