OP,

There are people out there that just cannot justify putting there life into the world for everyone to see.

Then there are people who hide the things they do because they cheat.

So, if you haven't seen any red flags, he treats you well, your in love with this person, etc. Then stop listening to them, maybe they are unhappy with their relationships so they project it out to the ones they are happy.

Could he be sneaky, Maybe. Could he be 100% honest, maybe.