yes,this manhwa was adapted from the original web novel and while the mystery unfolds from ch to ch, i'm gonna tell straight the plot...
*spoilers*
basically mc and ml were deeply in love in their past live but mc meets tragic death and then ml forms an eternal contract/vow with mc's soul.then ml spent hundreds of years entirely alone, watching the flow of spirits and waiting for mc's specific beacon to light up again. centuries later, in the modern era, mc was reincarnated into his second life. ml tracked the soul immediately. after the tragic accident of mc's parents, ml stepped in and became his guardian. for 15 years, ml raised mc with absolute care. He hid his godhood, suppressed his romantic feelings, and acted purely as a supportive parental figure. By night, he secretly used his powers to slaughter the malevolent spirits drawn to mc's marked soul.
At age 14, mc developed a secret crush on his unaging guardian. At age 20, mc blurted out his feelings during a drunken confession. Realizing mc truly loved him back, ml finally accepted the romance, and they became a passionate couple.
Around age 27, the immense, divine pressure of the ancient contract began physically straining mc's fragile human body.Due to this spiritual friction, a tear opened in reality. mc accidentally wandered into a restricted spirit domain and witnessed ml in his terrifying, all-powerful deity form, fighting monsters.The shock shattered the seal on mc's soul. Centuries of past-life memories flooded his mind. He realized the man who raised and loved him was a god who had waited an eternity for him. there were some rules due to the vow like physical and spiritual.in the end,To save mc from the physical toll of the tether, ml used his supreme divine authority to re-bind and stabilize the contract. They altered its rules so it would no longer harm a human vessel(mc). finally they became true emotional equals and at last a happy ending where they will be together for eternity

I don't really like to spoil much so hear me out
this doesn't seem right with adult ml meeting mc at age 5 but there's reasons for that (from their past lives) it's also supernatural and the story does have a happy ending. in the end they redefine their ancient contract(which is their souls are permanently connected for eternity)and mc lives a long life with ml but as ml is non human and mc is human so he will die someday but will reborn again and live with ml again and again for eternity... you know at first i was also like groomig?i'm outbut i read all the ch and it was a one time read for me