i think he would say...
Ridhimma maine tumhe us din dekh liya tha... mai janta hoon tumhare liye mujhe bhulana kitna mushkil hai...mere liye bhi tumhe bhulana utna hi mushkil hai. Jab tum mere bina aur mai tumhare bina nahin reh sakta toh yeh dooriyan kyon?😆😆😆 (it sounds so cheezy) mai yeh dosti ka dhong karte karte thak gaya hoon. Mujh me himmat nahin hai ki mai tumhare saamne sirf ek "dost" ban kar rahoon. Please ho sake toh mujhe maaf kar dena...lekin mai ab yeh nataak nahin kar sakta. (and he walks away)...and she sits there and cries.
followed by an confession very soon.