How do you think the story would've gone had Qi Heng proposed to Minglan before Gu Tingye?

Don't get me wrong, I am Team GTY all the way. I just have a soft spot for QH/SML and think that if things had been different, they would've had a happy life together.

Nothing would have changed. The family denied the proposal of the Duke family because she essentially had to marry Gu Tingye (granted by emperor and so on) but for Ming Lan, that was not the main reason. She never could have trusted him again after being essentially betrayed the first time.

Okay, but what if they got married before the Princess and her family could make a move?

Then Ming Lan would have stayed loyal to Qi Heng but would never felt as happy as she does with Gu because Qi Heng never understood Ming Lan truly. 

I would like to add that Ming Lan would suffer a lot more in the hands of the Duchess, because Qi Heng would rarely stand up to defend her from his mom, while GTY would support Ming Lan in any family dispute.

 NinaYuki:

I would like to add that Ming Lan would suffer a lot more in the hands of the Duchess, because Qi Heng would rarely stand up to defend her from his mom, while GTY would support Ming Lan in any family dispute.

Gu Ting Ye has only Ming Lan in his heart.  When a man loves a woman, she is his heaven and paradise, nothing else.

GTY will fight or kill for ML.  

Minglan would have made the most out of her situation but she would have silently suffered a lot. She was willing to take in concubines when she was with GTY, she only spoke up for herself later with GTY because he understood her and he made her feel comfortable enough to do so. Yuanruo was much more submissive to his parents, so even if his mother forced in a concubine, I'm sure he wouldn't have refused and neither would Minglan. He wouldn't protect her like GTY did, which would cause a lot of heartache. Also because Yuanruo is such a bleeding heart, if the other concubines treated him well, I think he would care for them genuinely. Minglan's life would have been like a lot of women back then, sharing her husband with others and not being able to say anything about it. She would still have happiness, as Yuanruo was loving and kind, but she would continue to live being restrained by her mother in law and having to play games in order to keep the household in order. 

Gu Tingye was 100% the right choice (even though it wasn't really a choice). GTY was the only man with the status and the personality that allowed Minglan to be herself and not have to compromise. I loved Yuanruo too, he was sweet and genuine, but in the times that they lived, Minglan needed someone strong and who understood her. 

What I have come to appreciate about this series most is how it shows the dynamics of family and household as well as expectations of different social classes. I believe she agreed to marry him despite potential issues associated with being low-born because he promised her he would make her number one and defend her fiercely. Unfortunately, he underestimated the influence his mother would have over his future - one that could not include Minglan as his number one. One chance was all he has, he blew it.  What if he was able to defy his mother and marry Minglan? Would it have had a happy ending? I think so. However, it would have been just as frustrating (and dangerous) as with Tingye.

The family had already realized their mistake and the Duchesse had already been humbled. It's my own opinion that even though Yuanruo is not an assertive man and a fillial son the dynamic in the house and based on the slap that the family had received in the past that it would have been a very harmonious alliance. I am in the belief that overall Ming Lan life would have been easier in that household not having to worry about her husband offending anyone or being in constant danger due to being a general. Would she had found the kind of passion that comes with loving a man of action like GTY probably not specially knowing that she was once rejected and betrayed. But she would have had an easier life there with a loving and devoted husband and a family that would have come to realize that she was indeed a hidden gem. Ming Lan is the kind of person that would have made it work anywhere. And I do believe that in no time she would have been running the house and the whole family. They would have been grateful to have her there and create stability in the household. 

All that said I am still in GTY corner and wouldn't have it any other way. This couple and  what they mean together is much better for the country and the overall story. Their kids should be leaders of their generation with parents like that ?

Agreed. I loved how things ended with Yanrua and his wife - she won him over with gentle persistence. They seem very well suited. Yanrua might have made a mistake, but he kept his promise to protect and defend. It was really cool how all four could be good friends.

I don't believe her ending with Yuanrou would have been bad. I also don't believe that he would be soft for others or not defend her from his mother. I am pretty sure Minglan would have won over Princess Pinging with her smarts and would have been in a loving relationship with Yuanrou. The only problem would be that she may continuing pretending to do the things that she doesn't like and etc. But if Yuanrou ever realizes the true Minglan, I believe he would have still loved her no matter what. He was sincere in his love for her, but just never made the right decisions and risks. Minglan would still love him as well for his sincere love to her.