Responses
My take on it would be he sort of set this open relationship - meaning they easily jump in to one's space. Seme also messages frequently. Then suddenly he goes off, can't give a convincing reason, and doesn't contact at least once.
That is indeed suspicious. Don't set that tone then take it back without any convincing reason.

Not defending the ML, but I know some of you too experienced not telling/hide something to your bf/gf specially the complicated/personal/family stuff when youre still new to the relationship. White lies would obviously happen here and there. In not saying it's right, but it's also not wrong if they choose what they can only share at that point of their relationship