Twilight Sparkle and Flash Sentry
[Original: Twilight x Flash]
Strong relationship, had their ups and downs before they got married, but once it settled down they decided to settle down and have never regretted it since. They meet when Twi went after Sunset to get the crown, Flash had been placed on a mission to every few years go into the mirror and watch Sunset to see if she was improving or declining. He’d swap places with the words original Flash, never telling that flash was his mission was, that flash slowly feel for sunset and started dating her, which male the equesrtia flash really akward to do his mission.

He never really told Twilight that it was him who she fell for until after they had started dating.

Rainbow and Soarin

• Rain x Dumbbell
  [Original: Rain x Soarin]
  Rainbow first dated Dumbbell in highschool, it was more of a rebound relationship for them both but it resulted in a foal. Dumbbell adopted the foal full time and Rainbow would visit her every so often. Rain dated for a bit before joining the wonderbolts, after joining she kinda stopped looking for love all together and gave up on it.
  A few years in and she get promoted to front line where she spends a lot of time training with Soarin. Hes a good 12 years older then her and gave up on finding love as well. After sometime things hit off and they fell hard and sudden for one another. Soarin knew of Rainbows previous family and loves her daughter like family.

Pinkie Pie and Pokey Pierce
[Original: Pinkie x Pokey]
High School sweethearts. Had so much trouble when they started dating, Pokey is 5 years older then Pinkie and was a bad boy, and was a bit abusive [verbally] to pinkie but she was naive and in love. They spend a bit to much time in the bedroom and it resulted in a foal(s). It was then Pokey had a life change, he never thought of being a father, his own was pretty shit and abusive and he really reflected on how hed been treating Pinkie, he change for the better, he couldnt change the past but he could be a better pony to her now and be the best father he could be.

Fluttershy and Big Mac
[Original: Flutter x Big Mac]
Meet when Fluttershy was caring for Winona after she’d had her first litter of puppies. They kinda hit it off but both really too oblivious to notice it. Big mac later went on to get drugged by the cmc to love Cheerilee and was kinda put off of love because of it for a little before he feel for Sugar Belle. They dated for a few years but Sugar realised she really wasnt into stallions and Big mac was the first to be told. He kinda saw it coming as he’d noticed their relationship had slowly started falling. He dated on and off with a few other mares before finally asking Fluttershy out.

Fluttershy was always too busy or too shy to really think of love, shed dated a few over the years (both stallions and mares, trying out different angles) but they never really went past 3 months. When Big Mac asked her out she was too shy to say yes, she couldnt figure out why but her friends, mostly AJ helped her realised that the reason she was so shy was because out how much she cared for him.

Apple Jack and Caramel

• AJ x Cheerilee
  [Original: AJ x Caramel]
  Caramel is 8 years older then AJ and was a total ladies man, he was very popular with mares but they never really lasted over a week each.

AJ was looking for some attention and Cheerilee was looking for some sexual attention, neither was really looking for a romantic relationship or any commitments. They started to spend more time together after Cheerilee was drugged by the cmc to love Big Mac. They would spend some time together and give eachother some sexual benefits but it wasnt until one late evening they went and had a little too much cider with Rarity that they decided to have a threesome of fun.
AJ woke up a stallion and very confused why her bestfriend and partner was with her. Later AJ and Cheerilee broke it off as it had gotten too akward, Cheerilee later sent AJ a letter stating that she was pregnant and feared the foal was AJ’s. A long 14hour labour and DNA test later, the foal was indeed AJ’s. Sure they way their child was conceived was not ideal, and Rarity dose take some blame for that, but AJ would never trade her foal for a re-do.

Rarity, Luna and Ember
[Original: Rarity x Spike]
Luna and Ember married to create a strong tie for ponies and dragons. There was so much disgust at their wedding on both side and they where both very unsure of if this would work. They had some feelings for one another, but was it really enough to marry on?

A few years into their marriage and it had gotten quite dusty, the marriage worked and ponies and dragons where getting along well, but they wanted to spice their marriage up. Luna had dated Rarity for a short time before hand (luna was in disguise, but rarity did know who she was dating) and luna suggested that they get rarity around to spice things up. It worked, it worked so well they decided to all get married, it fixed everything, it shocked equestira, not the fact it was a poly realtionships are quite common (called ‘herds’), the fact that luna had dated in disguise before hand was the shock.