Torn Between ECE at Manipal Jaipur and E&I at SASTRA Tanjavur: Which Should I Choose?

I recently join a new workplace and there I found this male married colleague of my age. At first everything is professional. He sometime message me on WhatsApp to just ask about office just in friendly way. I thought him as a workplace friend and we chat in a friendly way but one day he told me not to mention to anyone that he message me on WhatsApp. I found this weird. I mean it's nothing between us that should be hide then why he told me to keep it private.I want to confort him about this incident But then I think that maybe I overthink this situation and as we have to work together so I think it become awkward also o am very new at workplace so I sweep it under the rug. But next day he act normal at office like totally friendly so o think that I might be overthink about the situation. But later one day when he visit home he specifically told me not to message him. I mean I what is this. I never message him first. I only reply him. I never started it. If we are just friends why he want to keep it private. I find it little bit weird and also I don't like it. I want to comfort it about that but also not want make it awkward at office. I want to know that what kind of his intentions. I don't want any trouble.