Its difficult for me to judge because i have SAD anyway - so was always affected by the season - but i would say it has definitely got worse because there are none of the winter time consolations of lit fires and cups of tea made and above all hugs. In summer we can go outside and be among nature more easilly - i,ve always been an outdoors person - but having said that it too has its difficultys as thats when you see loads of couples around.
The only way to get through is to tackle each of these as they come up rather than trying to think too far ahead - generally day to day -
but i know things like xmas are hard to ignore - i decided i would compromise and create different traditions -so although i have lunch and buy presents for my grandkids i now look at christmas from the outside - some-one elses festival in which i am a guest for one part of - so instead of a xmas tree we decorate an outdoor tree with home made bird seed cakes and popcorn strings - the grandkids love that - even the older two who now get to climb the tree to put them up (something normally forbidden) - i dont send xmas cards - because i couldnt face writing them just from me - so i put stuff in the foodbanks and asked others to do the same rather than send them to me - but i make a handful of new years card for friends and my house is decorated to let in the light -(pagan new year tradition) - so it isnt devoid of festivity just different festivity and actually something more about me than xmas ever was - the helping nature and letting in of light - so something like that needs to be something that appeals to you and perhaps you do need to think ahead on - but the first year i just went along with what others wanted, took days off work on the anniversary and his birthday initially without knowing how i would actually spend them. then panning to either do a specific thing or do nothing if it turned out i couldnt cope with that. What i have found though is that the dread of them coming up was worse than the day itself and thats something many others here have said as well.