UNLV held a 12-point lead with 12:34 left.
That's when Colorado State went on a 15-4 run, highlighted by back-to-back 3-pointers by Avila and Octeus.
The Rams mounted the comeback without Bejarano, who picked up his fourth foul midway through the half. Bejarano entered the game with under 7 minutes left and missed his next four attempts.
UNLV scored the next nine points to pull away.
The Rebels led 41-31 at halftime after scoring 18 points in the paint and making six 3-pointers.