Hayden_panettiere_milo_ventimiglia Hayden Panettiere finally noticed that Milo Ventimiglia is like, really, really old (for her).

The "Heroes" costars — who started dating secretly in 2008 — have officially called it quits, according to Us Weekly.

The mag cites a source who calls the break-up a "lifestyle conflict. They were in very different places."

Yeah, she’s in that hot 19-year-old girl place, and he’s in the serious 31-year-old guy place.

That’s 12 whole years of way different.

Adds the insider, "There are no hard feelings."

Really, bummer. ‘Cause that would have made watching "Heroes" way more interesting if it had ended all ugly.

The source tells Us that Hayden likes to "go out in the Hollywood scene" and that’s not Milo’s "style."

Yeah, and again, there’s that whole "He was born 12 years before her" thing.

And here’s proof: Milo Ventimiglia steps into the Celebrity Time Machine!

What do you think? Can a girl, 19, have a serious relationship with a man, 31? For long?

Related Milo Ventimiglia and Hayden Panettiere news:

Don’t change clothes at Hayden Panettiere’s house!

Hayden Panettiere’s dad arrested on suspicion of abuse

Are Hayden Panettiere and Milo Ventimiglia getting hitched?

Read more "Heroes" news at Showtracker!

Photo: WireImage

Posted by:Elizabeth Snead