To answer the other questions:
Izzy apparently had a child when she was a teen and gave it up for adoption. Not aborted. Re-entered her life when a marrow donor was needed.
Dr. Webbers (the dude who was Skinner's boss on the X-files) is going through a divorce because of an affair. Now his 52-year-old soon-to-be-ex is pregnant.
Dr. Grey's dad abandoned her and her mother as a child for another woman. Grey has some serious long-term commitment issues because of this.
Izzy and George got drunk and had sex, causing him massive amounts of guilt for the affair. The plotline has been dragging on for weeks.
McSteamy (Multiple-Man from X3) and Addison tried to go on a sex-hiatus for two months. She challenged him to do this because he's some sort of man-ho. Then she ended up sleeping with somebody else. Thus spelled the end of that relationship.
And Cristina did NOT have an abortion. She wanted one, but then she had an ectopic pregnancy, bursting one of her fallopian tubes. Instant miscarriage, the ever-convenient answer to unwanted pregnancies on TV.
I agree, the people are stupid. Virtually all of their stupidity revolves around sex. But again, this continual game of Musical Bedsheets is FAR FAR FAR from consequence-free.