Is this a messed up love triangle (or, is it even a love triangle)?

I went to go and live with this family. I'm 18 years old and my name is Landon. There's this girl named Jessica whose 20 and her high school sweetheart and love of her life Jordan is also 20. Jessica has a 15 year old sister named Makayla. This/these weird things started happening. One day I was in my room and Jordan and Makayla went into the bathroom. They were in the bathroom for quite a while with the door closed. Suddenly I heard squeking in the bathtub. There was then nice cutortling accordingly. I then realized that they were having sex. They proceeded to have sex and then cleaned the bath tub clean. Another day I went for a drive. When I came home I found out that Jordan and Makayla were in the bathroom alone again. I heard Jordan moning and Makayla humming in reciprocal affirmation/ confirmation. Now, this is where it gets even weirder: one day Jessica and I were alone in the kitchen together and we just started having loud, raucous, animalistic sex together. We have to this day. I'm single, Jordan and Jessica are still a couple, Jessica doesn't know about Jordan and Makayla having sex.