Girlfriend and her brother went on a trip by themselves
For context, my girlfriend and her family are openly and actively incestuous. She opened up to me about this 2 months ago and we've opened our relationship to her family since then.
During the family retreat, I could tell my gf, and her brother were spending a lot of time together. And they even made love again in the morning before we left. After we got home and we talked about our experience and what I liked, she brought up the fact that she misses her brother and wanted to spend more time with him. She said that she and him want to take a vacation together, just the two of them, to a local spot their family used to live. She asked me if I was okay with that and I gave her my blessing. She and her brother are basically best friends, and I didn't want to undermine that. And this weekend, the two of them booked a hotel together and spent two nights (Friday and Saturday) with each other.
Since I wasn't there, my gf would send me occasional updates on what they were doing. The places they visited, the coffee they ordered, and the cute dates they went on (my favorite was a picture of them sharing a cute kiss in this community garden). They even sent a few photos of them together cuddled up naked in their hotel bed and a short video of her brother recording himself fucking her doggystyle from his POV. It was extremely hot and I was grateful they shared those intimate moments together with me.
On Sunday, they drove back to our apartment to unpack. My girlfriend and her brother wanted to thank me for letting them have their little brother-sister vacation, and we ended up having a really intense and long threesome and she let me cum inside her first.
Afterwards, I remember the three of us chilling in bed together shooting the shit about their family life and funny stories about each other. The whole experience made me feel a lot closer to my girlfriend and her family. I'm happy that we have this relationship while many would probably disapprove.