I am a New Member at Similar Worlds

Is it OK to "ghost?" When I'm PMing with someone, and I have to do something else, I always try to sign off by saying how much I enjoyed talking to them and that I have to go, so they don't wonder what happened. But I notice a lot of people just stop responding, so I'm wondering if that is acceptable. Because when it happens I assume they had to go and it's no big deal.