Financially secure?

A serial killer.....

a cheater....

smokers

There are so many possibilities here AND it depends on how you interpret the pronouns. The use of "they" could mean either party.

Having said that, I'll guess convicted of a crime.

Abusive

I agree with Dees, you can't tell whether the description requested would be of the breaker or the breakee. I'm guessing if the breaker became a lottery winner they would break up.

2nd guess: My sister once broke up with her partner because he erased her phone messages and couldn't remember any of them & didn't write them down. Yes. She's still single. :0)

I interpreted it as a "deal breaker" list.

always late

always broke

Hmmmm. . . . . .

Kind of partner isn't specified, either. Spouse? Business partner? Partner in crime?

I'll guess very dishonest.

Gay, or not gay, depending on the orientation of the 'breaker'.

Sloppy or messy.

Rusty

blanket hog or a snorer

Hmmm...the above all sound like deal breakers to me. However, Rusty's list is pulling me to sloppy/messy. Not exactly in the same category as serial killer but still a tough one.

Different religion...

drinking heavily

don't want children

addicted to the internet

of a different political party.