At the end of the "20 2020 Pennies" arc, Penny talked about her 1 in 20 chance of happiness, something she's also mentioned at other times, most recently when talking to Fred. Judging by the futures at the conference, three of them stayed with Rich, making him a 3 in 20 chance. But, one of those futures was with Aggie; by taking a 3 in 20 chance on Rich, she took that 1 in 20 chance on Aggie.
Why did Charlotte fight to stay alive after trying to kill herself? Because Cyndi told her she'd go after Duane next. Her desire to protect him from her gave her enough to fight to stay alive!