In the last episode Roseanne says that Darlene really went with Mark. I cant really see this happening, can any of you?

No I can't. She hated his guts. But I don't know if that is entirley true cause the series finale was totally confusing.

I can sort of see Darlene and Mark, but I think Roseanne was trying to make the point that she was changing things in her life that she didn't like by writing them the way she liked them. A lot of parents probably wish they could do the same with the boys their daughters bring home, sometimes.