Original Kanji and romaji:

愛すればこそ iあればこそ

aisureba koso i areba koso

If you listen to the song, it is obviously sung "aisureba koso ai areba koso"
So I assume that in 'i' they mean it to be pronounced in the english way, 'a-i' instead of 'ee'. Either way it makes for more singable lyrics.