Kuch kuch hota hai

Hi,
I am new to this forum and to watching hindi movies. I just watched kuch kuch hota hai and enjoyed it, especially kajol's performance. But parts of the plot really confused me, maybe you movie buffs can clarify for me. Does anybody know why througout the movie Shahruk says one falls in love only once and marries only once yet he loves second time and marries twice? Also around the end he is shown looking at rani's pic and then closes his eyes and sees kajol?
Thanks in advance for any inputs.

I do get what you mean i was confused about this but this is my theory i guess he was good friends with rani and fell for her because of her loooks and then obviously he married to her as well so misses her at the end. Kajol was his best friend , his real love and never saw beyond that and he was abit of a player at the time so never saw beyond her looks as well