My boyfriend of 7 months have been kind of distant recently, as he calls/texts way me less than before. Last night, he called me twice but I was busy at the time so I didn't pick up. I tried to call him back three times and he later texted me saying "Sorry for not answering, I'm a bit tired so I'm gonna sleep now. Talk tmr". I texted him goodnight and he replied "thank you for understanding dear". I got so confused because he never calls me "dear", and that was out of nowhere. Is this a red flag?