Sure... Succubi only appear in the dreams of men. If she had met an Incubus (the male version) it'd be one thing, but that still only happens in dreams, not in "another world". If she actually did have an odd experience she might have suffered or has been suffering bouts of sleep paralysis though which should be checked on.
Succubi would never need a leader in any way as they can go into anyone's dreams according to lore. On top of that, thee only reason an Incubus would come near a normal female would be when they are having sex with a male human to switch their demon semen with the human load (I kid you not that's apparently how people give birth to demons, silly crap.)
In other words, she's lying out her ***