Oh and another point that I failed to make about the garden. While Jirou's garden, his love for Aoi, is growing and blooming, Aoi developed a liking, an affinity, towards gardening. Aoi's love for gardening in turn symbolizes his desire to nurture and care for a garden, which in this case Jirou's blooming love for him. He wants to care for Jirou, he wants to watch over his beloved despite initial beliefs of a fake or mistaken love.
Fortunately, it's real love (already displayed by the two's fluffy, tooth-rotting moments as a couple, as a pair of lovers, fiancés, husbands). Also... Aoi's desire to nurture and make the garden of love grow, it also in turns symbolizes Aoi's words to Jirou during their honeymoon or lovemaking in the villa. And those words are: "More. Desire me more."
He doesn't mind rough sex with Jirou. As long as it's Jirou, then he's happy. And as long as Jirou's love, his infatuation with him grows, then he's satisfied. ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄ Such a passionate yet sweet, tooth-rotting couple aren't they?
Jirou and Aoi may not be super popular as a couple with everyone, but to me, they're just as powerful as a couple as Kudou and Miyauchi. ^^ I mean... Their fluffiness and lovey-dovey moments are ridiculously strong.
Jirou and Aoi met when they were young and was attracted to each other. We can assume that they know each other by name before they met face to face because of how they were known for being heirs to powerful families. Although Jirou pushed Aoi away after realizing that he's letting another force make decisions for him, falling in love with Aoi in this case, and returned to his household without any intention of contacting Aoi ever again. But the moment he came back, he still wanted something that'll remind him of his first love Aoi, which is the garden. The garden symbolizes the love he held for Aoi that continues to grow and bloom flowers.
On the other hand, Aoi, after leaving his family, decides to go somewhere far away, somewhere where he can be independent and start a new home. But upon seeing Jirou's father, he's reminded that there is one thing that hasn't changed and is the last thing he's had, Jirou. Aoi doesn't reject his feelings for Jirou and instead comes to the Saionji household with the intentions of becoming independent, but also to watch over Jirou attain happiness, which in turn as he said is his happiness. When he had his first heat, the first name he screams out is Jirou, who showed hostility and rejection, rather than Miyauchi, his butler who's almost like family and best friend to him. And.. Jirou reciprocated that, by being the one to immediately rush to where Aoi is with a frantic expression and even reprimanded the servants who planned on pushing Aoi around.
At some point, they feared that their feelings for each other are just fake or invoked by their soul bond, but Jirou's engagement with Hikari made things clear to both of them. Aoi's happiness is Jirou's and vice versa.
Even during their little honeymoon in the extra, Jirou is shown to be the romantic type who wants to be gentle and treasure Aoi for the times he denied himself and Aoi of happiness and precious times. While Aoi just wants to avoid making himself look humiliating or uncool in front of the person he loves. Then again, Jirou loves Aoi for the way he is. Furthermore, he would sneak out of parties just to check up on Aoi during his pregnancy. It's really endearing to see their moments together.
It's a little spoiler, but later on, Aoi tried to care for the twins on his own to allow Jirou to have some more time to study for his college stuff, but got reprimanded by Jirou instead. Jirou wants to do these family things with Aoi, whether he's busy or not. He wants to love Aoi properly and in his romantic way.ヾ(❀╹◡╹)ﾉ~