My ex asking me to go to her house?

She currently has a bf in which she is on and off with for over a year now. Now she is asking me to go to her house to help her study. before we even started dating we would make out at her house. Now, being a single guy, i naturally dont care if she cheats with me, so for me its a no brainer. but why would she even consider inviting me? theres so many other people that could help her "study"...