Nothing. It's just that when I read the english translation of 'That XX'
It seemed so sweet and thought of using it on my fanfic. My poor dead, lifeless, and withering fanfic.
So here's some of the translations.

Walking on the street, I bumped into your man (Yeah I saw him)
Uyeonhi gireul geotda ne namjal bwasseo (Yea i saw him)
I didn’t want to believe it, but my hunch turned out right (I told you)
Hoksina haetdeon nae yegami majasseo (I told you)
He’s not wearing that ring you gave him, there’s another girl by his side
Nega jun banjireul ppaego hanjjogen paljjangeul kkigo
But I’ve said enough (I don’t wanna hurt you)
Geunyang yeogikkajiman malhalge (I dont wanna hurt you)

Now you’re getting angry with me (Why?)
Geunde ohiryeo neoneun naege hwareul nae (Why?)
You say “He’s definitely not that kind of person” (Sure you’re right)
Geuneun jeoldaero geureol riga eopdae (Sure you’re right)
Seeing your eyes, I reply that I probably got it wrong
Naneun ne nunchil salpigo naega jal mot bon georago
See, I lied for you (I’m sorry)
Geurae neol wihae geojitmalhalge (I’m sorry)

I hate that you don’t understand me
Oh nal mollajuneun nega miwo 
I hate all this waiting
i gidarimi sirheo
Let go of his hand (break it off with him)
son ije noheurago
When you’re sad, I feel like I’m dying
Nega seulpeohal ttaemyeon naneun jugeul geotman gatdago baby

That XX, what does he have that I don’t
Geu saekkiboda naega motan ge mwoya
Why can’t I have you
Dodaeche wae naneun gajil su eomneun geoya
That XX doesn’t love you
Geu saekkineun neoreul saranghaneun ge anya
How much longer are you going to cry yourself silly?
Eonjekkaji babogachi ulgoman isseul geoya

When you speak of him, you look so happy (you look happy)
Neon geu saram yaegil hal ttaen haengbokhae boyeo (You look happy)
It’s good that you can be this happy (I’m happy)
Ireokerado useuni joha boyeo (I’m happy)
You say you really love him, want to be with him forever
Geureul jeongmal saranghandago machi yeongwonhalgeorago
You trust him completely (I don’t know what to say no more)
Mitneun ne moseubi (I dont know what to say no more)

Your friends all know that guy (yup they know)
Neoui chingudeul modu geureul jal ara (Yup they know)
It’s so obvious, why can’t you see (it’s you)
Ppeonhi da boineungeol neoman wae mot bwa (It’s you)
They say love is blind, Oh baby, you’re so blind
They say love is blind oh baby you so blind
Please, I beg you, break it off
Jebal heeojigireul baralge

Oh I hate that you don’t understand me
Oh nal mollajuneun nega miwo
I hate all this waiting
i gidarimi sirheo
Let go of his hand (break it off with him)
Geu son ije noheurago
When you’re sad, I feel like I’m dying
Nega seulpeohal ttaemyeon naneun jugeul geotman gatdago baby

That XX, what does he have that I don’t
Geu saekkiboda naega motan ge mwoya
Why can’t I have you
Dodaeche wae naneun gajil su eomneun geoya
That XX doesn’t love you
Geu saekkineun neoreul saranghaneun ge anya
How much longer are you going to cry yourself silly?
Eonjekkaji babogachi ulgoman isseul geoya

Rap)
Expensive cars, beautiful clothes, high-class restaurants, they all suit you well
Bissan chae yeppeun ot gogeup reseutorang neon jal eoullyeo
But that XX beside you, he doesn’t suit you, he really doesn’t
Hajiman ne yeop geu xneun jeongmal anya neorangeun an eoullyeo
He smiles like a hypocrite with you, brushing your face and hair
Ne apeseo geojitmisoreul jieumyeo ne bolgwa meoritgyeoreul manjimyeo
But he’s thinking of another woman for sure, how dare he
Sogeuron bunmyeong dareun yeojareul saenggakhae

The amount of tears you’ve cried, I want to make you happy by the same amount, baby
Eojjeom geureol su inni joe gatae
Rather than going through the pain alone, share some with me, baby
Nega heullin nunmulmankeum naega deo jalhaejulge baby
Please look at me, why can’t you realise that I am your love
Neo honja gamdanghal apeum naegedo jom nanwojullae baby
Why are you the only one who doesn’t know
Na jom bwadallago geudae sarangi wae narangeol molla
Wae neoman molla

That XX, what does he have that I don’t
Geu saekkiboda naega motan ge mwoya
Why can’t I have you
Dodaeche wae naneun gajil su eomneun geoya
That XX doesn’t love you
Geu saekkineun neoreul saranghaneun ge anya
How much longer are you going to cry yourself silly?
Eonjekkaji babogachi ulgoman isseul geoya

That XX, what does he have that I don’t
Geu saekkiboda naega motan ge mwoya
Why can’t I have you
Dodaeche wae naneun gajil su eomneun geoya
That XX doesn’t love you
Geu saekkineun neoreul saranghaneun ge anya
How much longer are you going to cry yourself silly?
Eonjekkaji babogachi ulgoman isseul geoya

Sweet isn't it? <3<3<3