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No one actually knows. It's just based off a single piece of dialogue where Mo says something along the lines of you're back. But that could mean literally anything.
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Oh yea, I guess you're right. Actually, He Tian gives Mo a present which are condoms. I don't think He Tian would give him a present like that out of the blue after meeting him after x number of years (i don't know, maybe months?") it just doesn't seem fitting. Maybe they're busy with jobs and only contact via phone or text.
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sry for making u worry. There is actually no proof that Mo and He Tian part ways for a long time. This was based off my own assumption in this one chapter that He Tian saw Mo working and says "You have to overtime even on Christmas?" and Mo responds "you, when did you get back?". Actually, it more or less sounds like He Tian coming back after a trip or something. idk. (the chapter is 224). If He Tian left for a long time then came back, Mo would've been more surprised or something.
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I think he tian was just visiting someone or some people during the holiday because it was chrimtmass at that time
...If Mo gets there and He Tian is like "why're you so scared?" and he doesn't understand that the pic made it look like he was hurt, and he says to Mo in a sort of playful joking manner like "huh you were worrying for me, ;D ?" and Mo just yells out in anger, worry, and frustration "DAMN RIGHT I WAS! I THOUGHT YOU WERE HURT!" which would shut up a stunned He Tian. However, from there, I can also see a problem forming that might break them up. After Mo would be angrily yelling how he was scared for him, He Tian would then look at Mo surprised, and Mo, realizing what he said, would get even more angry and yell something, might potentially saying something like "you're crazy, you hang out with scary people, I don't want to be involved, blah blah blah".
We know that in the future Mo had parted from He Tian. (I don't know about Xixi and Jian Yi tho). What if He Tian, realizing he's causing nothing but trouble for Mo, stops harrassing him and only then gets back at him after he leaves his older brother and gang? As much as I desperately want them to be together, I know that He Tian is actually beginning to see Mo in a new light and might refrain from contacting Mo for Mo's own sake. After all, the restaurant scene with Mo and He Tian made me realize that their relationship has been somewhat smoother