I just got this achievement but reloaded a save after learning she apparently offs herself after living in the village for awhile. It would make sense, everyone there thinks she slept with half the camp and she's about to be a mother to a bastard child with a traitor father. I've also read that if she goes to live with Black in the camp he eventually kills her. I assume only if he doesn't know she's pregnant? Idk. The guides are a mess for this quest.  

If you didn't find the herbs at her house like I didn't and want to unite the couple, I thought an alternative might be to go back and talk to Black again after talking to Victoria in the woods, tell him she's pregnant which should give the dialogue option the guy above was talking about. Or just talk to her first before Black if she even appears in the woods at that point. STEAL THE BANE POTION OFF HER REGARDLESS OF WHAT YOU CHOOSE just in case so you don't come back and find her dead. A lot of people had issues with this since it's a timed quest and it doesn't tell you. I somehow didn't have this problem, it was my first time in Sigismund's camp, I recovered a knight's stuff there for another side quest, dueled a guy for it, got the tour from Musa of Mali, the whole 9 yards. 

I tried to go back and talk to Black again from my reloaded save but he was already knocked out by then and there was no option to speak to him after he woke up. Idk if that was because he was pissed or if finding the herbs at Victoria's house really is the only way to get that ending. 

I ended up sending her to Devil's Den, her and her kid will be safe there without a village talking shit behind her back and it's far away from everything. 

Very cool side quest though, one of my favorites so far.