In this story Mon-El didn't leave and go to the future ..... they still manage to defeat Rhea and got rid of all the other Daxamites but thankfully Kara sent Mon-El to Barry's Earth instead of into space .... And she visited him almost every day while Lena worked on a cure for his lead allergy , around 5 months later he was able to come back and they have been together ever since and now they are finally celebrating Christmas together !!! Hope you guys like this short-story !