I think MC had crush for ML but can't confess to him (ML ignoring him). Then, every night MC dreaming about ML. ML in MC's dream very kind to MC and spoiled MC every night.
Unexpectedly, fake ML in MC's dream world have his own consciousness and want MC for himself. Fake ML want MC forget about real ML and see fake ML as the better version of real ML.
But as story goes on, the relationships between MC and real ML got better and turn into romances. Fake ML realised this situation and trap MC into dream world and making MC can't awake in the real world. So real ML entered MC's dream world to saving him.
The ending is MC choose real ML and leave the fake one behind. Fake ML wailing and begging him to not leaving the dream world 🙁