I can never truly make up my mind about my headacanon(s). Somethings have changed, other have not. Perhps I should just put some descriptions of these instead of ramblin. OK? OK.
Apple Jacquelin and Caramel Chance-a-Lot: This has changed. Applejack and Caramel met at the annual Appleoosan Rodeo and hit it off well. Applejack had recently been through a rough divorce from her husband of 11 years (Troubleshoes Clyde) and was trying to raise her four kids alone. The two had met before several times and knew their families were close. They both had an understanding of failed marriages, as Caramel was divorced as well. Applejack's oldest child, Gingergold had a hard time warming up to him but tried her best in order to prompt her younger brothers to better acclimate to their mother's new boyfriend. Soon after they started seeing each other, Caramel urged AJ to follow her dream of starting her own business. She had already take ownership of Sweet Apple Acres, but, as with when she was a filly, desired to be an entreprenuer of her own accord. Caramel cheered her on and took resopnibility over the housework and child-rearing while AJ began assembling the necessary resources to start her own company. From all this came the company, Hothoof Cider and Mead Inc. which grew rapidly in popularity. After the company started to ease out, AJ and Caramel got to spend more time on their relationship. Shove came to push and finally the two came to realize they wanted to be together.
Rainbow Dash and Spitfire: This has changed. Throughout the first few years as a Wonderbolt (after the Second Great War) she grew very close to Spitfire (already having a preexisting crush on her). They began to spend more free time together and through a bit of snooping and perhaps a very awkward holiday visit with Spitfire's family, it was revealed that Spitfire was not born female. She was born a colt named Wildfire and began his transition after high school when he left for the Wonderbolt Academy. Spitfire's parents have never truly understood but like Rainbow dash nonetheless (actively teasing Spitfire about how nice of a daughter-in-law she would make). Spitfire and Rainbow did begin a romantic relationship, but never got around to getting married. They had a son (no magic alterations needed) and were overjoyed. However shortly after their child's birth, Rainbow Dash suffered a minor stroke and lost some fine motor control and tactile sensation in the right side of her body. Because of this she had to retire early from her Wonderbolt career. For all her great deeds to the country, the University of Cloudsdale (where she took some classes) gave her an honorary doctorate in Aerodynamic Physics. With that Rainbow applied for a teaching position and became a professor of weather manipulation and Aerodynamics.
Fluttershy and TreeHugger: This has changed. Now Fluttershy and Treehugger aren't completely romantically involved. Treehugger is still very much a free soul and doesn't mind free love where she can find it (from both stallions and mares) and Fluttershy is a bit more reserved when it comes to sexual intimacy, but they live together and take care of their adopted daughter, Hazelnut. Flutters is a doctor and runs a general health clinic in Ponyville and Treehugger is an "herbalist" and holistic medicine salespony. The unison is somewhat nice, Fluttershy can diagnose and prescribe clinical drugs, if you still find yourself in discomfort, Treehugger can set you up with something to take that ache away. They have a well balanced home and professional realtionship.
Rarity and Ellison Fancy Pants Trottington: This is the same.
Pinkamena Diane Pie and Cheese Sandwich: This is the same.
Twilight Sparkle: This is the same.