I wouldn't doubt it if Rachael makes a comeback in either the webcomic or a sidestory. She'd probably be the single divorced mom that begs one of her Xs to take her kids off her hands or something.
And to answer anyone's questions about playboy Fisk in detail. He did have sex with countless women before he got involved Elizabeth. He's even told her about some of them. But as soon as he got engaged to her he quit fooling around all together. Unfortunately that's what left Red blue balled for so long. There's no way Fisk would even consider cheating on his wife. He even burned his bachelor couch in a manner akin to a Viking funeral