Now that you mention it... Last time I saw them together was when they last shared a bill (the Jandaeng fight/Mabuza rematch)
Yeah most likely because conflicting training schedules and can also be attributed to the promoters. They should be providing tickets for fighters special apperances.
It isn't that they aren't close. I remember they were nervous about each other's fights and cheering one another on for the Jandaeng/Mabuza card. In the pre-recorded video segments they showed that night of the two hanging out, they seemed pretty tight as well.