In the new issue of "Vanity Fair", Jennifer Lopez talks about how difficult it was to leave Marc Anthony.

She says, "This was the hardest decision I've ever had to face. I really wanted this family to work. That was my biggest dream, and I worked hard at it. We both did.

"Sometimes it doesn't work . . . and that's sad. But I remain an eternal optimist about love. I believe in love . . . It's still my biggest dream."

As for WHY it didn't work, J-Lo didn't share any details we might actually WANT to hear. But she did cough out some vague, philosophical dog mess.

She said, "Sometimes we don't realize that we are compromising ourselves.

"To understand that a person is not good for you, or that that person is not treating you in the right way, or that he is not doing the right thing for himself . . . if I stay, then I am not doing the right thing for me.

"I love myself enough to walk away from that now."