Coming to Dev.I will not call him mama's boy now .Yest in that scene he was about say aap bahar nahi n stopped.Dev does not consider Sona has bhar wali.But his mom words hurted him n he said that he will handle it.So I hope Handling means saying the truth about Sona to his mom soon.Also he does not want Sona to get hurt.Already Sona is afraid what if his family says no.So to save Sona from getting hurt he hided that thing to Sona.
Even before Dev fall in love with Sona.He did not consider Sona as bhar wali.Remember the epi were Sona stitches Dev button.In that epi.He sneezed.Sona said to have him water n asked him wait for few mins .Then go.Mami says only ghar walo can do something.Dev leaves from there.Then next scene we see him sitting outside for few mins.Sona says Mr.Dixit don't consider me as outsider.
Only one wish I had Dev could have said Sonakshi has become his frnd.So he shared it.