
Neither are what we average Joes consider 'normal and healthy'. One's a mafia boss, the other works for the mafia as a subordinate.
Both are in love with Fei, Yoh more so. Also Yoh would probably be more devoted and gentle. If I looked at it objectively, Yoh is a good match...
So now, It's all about how Fei feels. Fei has a choice to make. Bad boy Mikhail or nice guy Yoh. Considering the events of the latest plot-chapter, Mikhail has a good chance. While Yoh is a good match, that is obviously not what Fei wants, or they'd be together as we speak.

Things are looking good for Mik/Fei.
But Yoh is still in with a shot. After all, he betrayed Fei, but Fei still forgave him and let him stay by his side. There could be more to their relationship than YA has let us know.
Lots to consider...
https://i.imgur.com/iBkS2d9.gif
I know I won't be resting until Mik/Fei are at the alter!
I think Fei Long just really needs a friend. He’s so starved for affection he even dreamed Tao was an adult who pushed him down. He needs something normal and healthy.