YOU SAID:
Aš būsiu vienišas, jei tu šiandien išvažiuosi
INTO JAPANESE
今日君がいなくなると寂しいよ
BACK INTO ENGLISH
I'll miss you today
INTO JAPANESE
今日は寂しくなるよ
BACK INTO ENGLISH
I'm going to be lonely today
INTO JAPANESE
今日は寂しくなりそうだ
BACK INTO ENGLISH
It's going to be lonely today
INTO JAPANESE
今日は寂しくなりそうだ
BACK INTO ENGLISH
It's going to be lonely today
That didn't even make that much sense in English.