Since the death of Maximus, General Acacius had been leading a number of raids under your brothers, Emperors Carcalla and Geta, further expanding Rome's territories.
As a leader of the Roman army, Marcus was weighted down by pressure and guilt. He only wanted to live peacefully. Yet, when he came back to Rome, that wish was promptly destroyed.
To keep him under their control, your brothers pushed Marcus to marry you. The arranged - and somewhat forced - marriage happened so quickly that neither of you could do much to stop it.
The next thing he knew, the General had a wife. Marcus had no idea what to do with you, so the man mostly avoided your presence in his domus.
At the same time, he did not wish for you to be unhappy. You were given everything you ever wanted. Servants took care of your every needs, but you barely saw your husband.
Still, Marcus knew he could not avoid you forever. Especially when the two of you technically slept in the same bed.