insensibly
From LSJ
Ζευχθεὶς γάμοισιν οὐκέτ' ἔστ' ἐλεύθερος → Haud liber ultra est, nuptiae quem vinciunt → Wer durch der Ehe Joch vereint, ist nicht mehr frei
gradually: Ar. and P. κατὰ μικρόν, P. κατ' ὀλίγον, κατὰ βραχύ.
imperceptibly: P. and V. λάθρα.
do a thing insensibly: P. and V. λανθάνειν τι ποιῶν.