This can be in person after you've met (and decided to keep seeing each other) or during basic conversation prior to setting up potential dates. "If they seem really engageing, then disappear at weird times for no reason, they may be unable to message because they are with their significant other," says Bennett. Even on the apps, if they go days and days without responding and don't ask you out, it could be a sign they are going through ups and downs with a partner and can't commit, as a single would.