Dragon's Dogma 2

I was able to get this in about 5 minutes using the home in Bakbattahl.

The "dwelling" in Bakbattahl will cost 30k gold, you just need to go up to it and talk to the NPC outside to buy it.

The reason this house is better is because there are a few NPC's that you will always see right outside the home that we can get to Max Affinity or basically fall in love with you.

To do this talk to them and choose the option to give gift ( on xbox) and select a valuable item to give them. If you have Bunch's of flowers, jaspers, onyx, etc.. these work best but can be done with other items. You will know they like this gift by the reaction they give you. Do this with two of the NPC's right by the house.

After you give them a gift go back to your house and rest till morning. The reason you need to do this is because you can only increase a NPC's affinity so much in a day. It took me 4 days of giving gifts to get two NPC's to fall in love. You will know they love you because when you talk to them their cheeks will glow red/pink.

Once both NPC's outside your home love you pick them up and bring them inside and they will fight to the death for your love and you will get the achievement.

This achievement requires two or more NPCs with Max Affinity to follow you to your home and start a fight with eachother. You will know that a NPC has Max Affinity when their cheeks are rosy and they don't struggle when you pick them up.
There are several long NPC questlines that end with the NPC falling in love with you and will visit you at your home to give you gifts. Especialy the maisters. You could wait for them to visit but there is a way easier solution for this achievement.

The fastest way to get this is to romance a bunch of random NPCs who hang around your house regularly. I would give 4 or 5 of them a random gift each day and sleep to repeat the process. A bouquet of flowers will get a strong reaction but I think anything will do. I used a bunch of Jaspers because I had a bunch of them in my storage. To gift an item you need to start a conversation by holding B and then press X.
After a couple of days you will notice their dialogue change and after a while their cheeks will go pink. If you have romanced at least 2 of them you can either lure them to the entrance of your house or just carry them there. After a short while they should start fighting. This solution will also advance the "The Philanthropist" achievement.