3. They get notifications from dating apps
Sure, they might tell you that they're not on Tinder anymore, but if they haven't deleted the app yet, it's a sign that they aren't completely invested in you. And let's face it, no one wants to be seriously dating somebody who is still keeping their options open.
4. They always take calls in private
There's really no excuse for this one. Even if they're having an awkward chat with their mom, they should be comfortable enough to have it in front of you. Otherwise, they've got someone on the other end of the line who you probably wouldn't want them talking to - like an ex.
5. They're glued to their phone
This is a red flag for two reasons. Firstly, if you're dating someone, they should have the common courtesy to put their phone down when spending time with you, and, secondly, it could be permanently glued to their hand because they've got something fishy to hide.