The ML also falls in love with the MC who treats him with kindness & care. He is very much in love but also very emotional and struggling with low self esteem. So he is hurt and keeps pushing hard the more the MC tries to create distance. The ML ignores/forgets the MC's explanations & boundaries, he just wants to consummate the relationship, then cried & gets depressed when the MC doesn't want to. The MC even tried to take a precaution of clearly rejecting a romantic relationship from the start. Even when the MC later tells him a version of the truth as to why they can't be together, the ML still pushes. Fortunately, the MC does have feelings for him and it's eventually okay/profitable that the ML never listens and uses every emotional tactic to get closer... Otherwise such pushiness after several rejections would be annoying & intrusive. Though the MC is a knuckle head that is scared to face his feelings because of his future (of returning back to modern times after 10 years), the ML is even ready to settle for a short term relationship. This drags the relationship dynamic as they face the same issues repeatedly, it's a push & pull.

The MC has to return to his original world after a specific amount of time. As a result, he decides not to have a relationship with the ML and to discourage the ML's feelings. Fine. This is actually a great plot point, and having him deal with the conflicting feeling he's developing for the ML would have made a great story. That isn't what happened. Insted he leads the MC on, is intentionally cruel, practically pushes other men on the MC, and then at the end gets possessive. Also the ML can come across as a dependent doormat with all his self-worth issues unresolved and overcome with the power of 'love'.