Archie Lyndhurst's girlfriend Nethra Tilakumara shared an outpouring of grief on what would have been their second anniversary.
Only Fools and Horses star Nicholas Lyndhurst's son died aged 19 from a brain haemorrhage at his family home, in September last year.
It is so rare only 800 people die a year from the condition.
In his memory, Nethra marked the milestone of what would have been their second anniversary as a couple.
The actress penned a heartfelt open letter accompanied with a showcase of their candid photographs from their time together.
Her loving words captured how her life had "completely changed and all for the better" when she met Archie.
She wrote: "To my best friend, Happy 2 Year anniversary, my love.
"Archie, when I met you my life completely changed and all for the better. You’re a once in a lifetime kind of boy… and I can’t believe my luck, that I found you.
"I really can’t. I only wished for so many more years and all I can say, is that when you know, you know- and I did.
"Thank you for making me laugh from the day we met, thank god I found a boy who could put up with my snoring. :’)
"Everything was always an adventure, everything was always fun with you, being with you was being at home."
Nethra paid tribute to her late boyfriend as she hailed him as a "beautiful, gentle, incredibly kind, erudite, thoughtful and insanely talented young man".
She added: "Looking at you in a room filled with people, was just seeing home. You were my home. Thank you for unconditionally loving me and thank you for making me a better person.
"I will never meet such a beautiful, gentle, incredibly kind, erudite, thoughtful and insanely talented young man again.. oh and also very funny ;) and I’m not the first or last person to say this.
"April 12th, the day that I will cherish for the rest of my life. Happy 2 years beautiful boy, I love you. I’m so glad I found you and I’ll find you again one day... X."
His parents Nicholas and Lucy laid their son to rest at a tiny chapel in November.
Archie followed in his dad's footsteps into the acting world after his father played Rodney Trotter in Only Fools and Horses.
He made a name for himself following his breakout role in CBBC series So Awkward.
