
He stopped caring about the twink the moment he agreed to do the contarct
(Also avoiding him by sending gifts instead, even going far as playing sick on his bday)
Nanjo is clearly drawn to mokyeon, maybe he is a little confused
But atp it is clear he continues with this pretense just to stay with mokyeon and sperate him from the twink

i think it's clear he feels less for the twink and has feelings of affection for mokyeon that ig he's confused about himself...but he still rushed to "protect" the twink from mokyeon after the choking thing, i think he's confused about how he feels and how the other two feel - i think he's confused by if mokyeon is toying with him or actually likes him. he also has his savior complex instinct so i think he has a tendency to rush to help the "weaker" party

Nanjo is confused I agree
He needs confirmation that mokyeon is serious and not just playing him like you said
I won't be suprised if he believes mokyeon is sleeping with for the same reason- being in love with twink and nanjo is the subsititue..
Either way, mokeyon was in the wrong on the chocking part .. that was too much but he didn't rush to the twink's rescue like it will be expacted from someone who is in love with somebody...
If your loved one is in a distress, you will rush to them, maybe even lose reason in the process right?
Starting to drawn in a spiral of emotions like anger, rage and protectivness.
I believe Nanjo is testing the reason behind mokeyon's actions untill one of them confess...
is he really just kind of blindly in love with the twink and still putting up with all of this from mokyeon because of that? he seemed affected by how well mokyeon and the twink knew each other at dinner and how they even cater their eating habits towards each other - if we assume he's just into the twink then it would be bc he's jealous and wary of mokyeon (like how mokyeon perceives it).
BUT if he actually doesn't straight up hate mokyeon and is not that intl the twink anymore then it would be just him feeling confused and feeling played by the two of them? idk he's actually pretty frustrating too he doesn't seem very in touch with his emotions