Maybe because it was implied he was trapped and sealed by the god who favors Lina so now Lina's influence is waning he was able to appear to Seria but not completely free.
Why the god favour lina tho,.?
Dunno but if I remember correctly the god who favors lina antagonizes the goddess who favor Seria that's why the god who favors lina destroyed the original timeline where rouche and seria married and manages to create new timeline the one portrayed in the novel where lina is inserted to which the goddess who favors Seria tried to destroy again and reset it to this current timeline.
She is definitely going to be pregnant soon right? Lmao. He is so thirsty and I love it but why is the Angel dressed like that??? Why a BDSM angel?! I loved it but why lol