Guy im seeing goes cold-PLEASE HELP

So I've been seeing a guy for about 2 months now. Weve spent quite a bit of time together now, stayed at his apartment a few weekends also and things have been amazing. Since we both work alot and him over weekends also, he said he wanted me to stay a weeknight so I did. Everything was perfect, he kissed me goodbye for work and as I start later said to make myself at home till I start. i sent him a few snapchats with his dog and he again told me to help myself to breakfast etc. I cleaned the house and left a note to say hope he had a good day and that I'd miss him that night. I then left for work and later that day thanked him for the energy drink he gave me to take but never heard back.

That night and the next morning I received msgs from a girl saying that if I man doesnt reply it's a sign to leave him alone and that I need to find someone my own age (hes 4 years older)..

I havent heard from him and i'm trying my best not to get upset but i'm not sure what to do. Should I wait for him to talk to me? Should I ask him what's going on or should I reply to the girl and ask her?