Rashi on Numbers 5:31/רש"י על במדבר ה׳:ל״א

1ונקה האיש מעון THEN SHALL THE MAN BE GUILTLESS FROM INIQUITY — This means, if the waters try her (have effect on her), he should not worry and say: “I have incurred guilt through her death!” — No, he is free from punishment. Another explanation is: As soon as he has made her drink the water and she is proved innocent she may lawfully remain with him as his wife, and he is free from sin in permitting this, but if he lives with her before this, he is not free, for a סוטה (a wife suspected of infidelity) is forbidden to her husband pending her trial (cf. Sifrei Bamidbar 21).