she didn't really cheat. Basically, he just got jealous of her relationship with tyler. He wanted open relationship. He dated Rayna first, bryce kinda didnt like that. Eventually, He stopped. Bryce and tyler got feelings. Jay (bf) got jealous after that he wanted to go monogamouous. Too late bryce wanted to keep an open relationship. So they broke up. This has already been discussed. just gotta go back a few pages and read it