I've noticed there's a lot of profiles who obviously haven't touched the app in months, and makes it harder to tell who is actively using and checking their profile vs. a "dead" account. I think it would be non-intrusive (if there are concerns of privacy for adding a "last online" feature) to simply make those inactive profiles be set to be private (no one can see them on the main overview) until they log back on again. The length of time before this activates could be set by the users themselves (a week - a month, etc.) possibly with a default setting of a month. This way, new and active users can be sure that the people they reach out to are also actively using the app and will actually see their likes and messages.