I’ll do Valentines day if you don’t mind! 😀 (I sort of missed out on new years stuff. Oops.) 

• First would be waking up to breakfast in bed. He’d probably have made Ignis teach him a pancake recipe and have practiced until it was perfect. 
• Next, he’d tell his S/O  to get up and get dressed, because he was taking his s/o clothes shopping for the reservations he’d made for that night. 
• It wouldn’t be often you’d see Gladiolus Amicitia in some fancy high end shop, but he’d do it for his s/o. The clothes they’d get would be elegant, and he’d say is was his treat. He’d want to spoil them until it was time for their dinner reservation. 
• It’s usually not a huge part of his life but being that he is the shield he can afford a lot. New jewelry for his s/o, maybe a hair appointment, or even a spa treatment for them. He’d make the day about them.
• Then, both of them dressed in elegant clothes, would step out for the night. He’d have rented a limo, despite how frivolous that would be, simply because the night would just be about having a fancy night on the town. 
• The restaurant would be fancier than either of them are used to, but they’d have fun while stumbling their way through dinner. (And they are far from the only couple having trouble with the fanciness.) 
• After that, he’d take them out dancing. He’d want this night to be special. It was the day of love after all. 
• Afterwards, maybe they’d go out for drinks, but not to get drunk. Just to relax. 
• They’d tease each other, and do their best ‘citadel snob’ impressions while talking to one another, and fall to pieces laughing. 
• After that, they walk home, hand in hand. Enjoying the night air and each other’s company. 
• He’d kiss them on their doorstep, the place where they had their first kiss, and tell them how much he loved them to end the night out.