You are right.
1,4,3 stands for the I love you if
1=I (one alphabet)
4=Love (4 alphabets)
3=You (3 Alphabets )
The meaning of the 25,5,19 is really different. It has different logic.
25 for Y
5 for E
19 for S
The code 25,5,19 indicates the number of alphabets and the code 1,4,3 indicates the size of the word.
25 for Y ( Y comes at 25 number )
5 for E ( E comes at 5 number )
19 for S ( S comes at 19 number )
A girl or boy saying YES.
If we want to create a code for NO then -
N - 14
N comes at the number 14 and O alphabet comes at the number 15.
A Boy or Girl can say 1,4,3.
A boy or Girl can reply 25,4,19 or 14,15,
1,4,3= I LOVE YOU
25,4,19 = YES