Let’s take AB as pair 1, CD as P2 and EF as P3
The number of ways these 3 pairs can be arranged = 3! = 6
But each pair can be seated in 2 ways = AB or BA
The number of ways, the 6 friends can be arranged (desired way) = 6 x 2^3 = 48
Total number of ways the 6 friends can be arranged = 6!
Probability = 48/6! = 1/15
Thank you so much