Can someone summarise me please? Also, is it love triangle and is it green flag or not?

So the main character has low high yin energy so he has to take yang energy from the main lead so he uses the main lead for his excessive yang energy to stay alive but then later on he starts to fall in love with the main lead. But the problem is that the main lead already has someone in his heart but that person drowned because of him so he is not yet over him. Also the ml's father is an asshole who sends a fraud to pretend to be the same person who ml wants but later ml starts developing feelings for the mc. Now the fraud finds the mc and tells him to leave him and the ml alone. The mc is disheartened and decides to forget him. But finally the ml finds the truth and wants to clear everything up but the mc faints because of lack of energy.