#1. He's a d*ck.
She'll probably agree with you in a few days/weeks/months but for now she still loves him and it hurts to hear that.
#2. There's a plan for you.
So this plan includes pain and torture? She'd rather make her own plans, thanks—involving tequila and pizza.
#3. At least...
Nothing that comes after this phrase is going to help her. Her heart is broken. Her world is shattered. There is no 'at least'.
#4. I never liked him anyway.
#5. There are plenty fish in the sea.
BUT THAT ONE WAS HER FISH. SHE DOESN'T WANT ANOTHER FISH.
#6. Do you think he's gay?
It's very sweet that you think the only logical explanation for someone rejecting her is if he fails all females, but no.
#7. He didn't deserve you.
Her head knows this, but her heart is so not there yet. Her heart wanted him and he rejected her.
#8. You weren't dating for that long, why are you so upset?
Sorry if her feelings don't fit into your official time frame on things.
#9. He'll realise his mistake and come back.
Secretly, she's hoping for this; please don't encourage her.
Here are the 3 things you SHOULD say:
1. I'm so sorry, it must suck.
2. Here, eat this pizza.
3. Here, drink this tequila.