Yes OP I have felt exactly the same, I've felt a lot of things over the course of the pandemic but never sad, however this week I just feel really sad and hopeless. Can't even blame the weather as its been glorious all month pretty much here.
I feel there is nothing to look forward to and I'm sick of not doing anything nice even just little things, everything is an effort due to covid, has to be booked, then you go and it's a severely reduced experience at best to terrible at worst (which often) - because of covid/Brexit. And don't get me started on masks (I'm in Scotland), I fully support them but I'm getting the worst maskne, my skin has been OK for years but is now terrible every time I have to wear one for more than 30 minutes, it was getting me down so much. I've severely restricted where I go so I don't have to wear one but feel I'm missing out and this is making me more depressed. I just want to do simple things like take DC to indoor play areas, museums etc. Or just browse the shops.
I'm having friend problem to @KurtWilde we moved to a comp new area last spring and have made connections, two of the women I thought were becoming close friends have relegated me into the 'playdate friend zone' still happy to do that but not interested in dinner out or coffees any more, no chatty happy messages or kisses on messages etc. - which there were previously lots of chatty messages back and forth losses now short or just emojies. And I F,ing hate the thought of playdates being my sole form of socialising, one of the DC's is too young really and mine is going through the not sharing phase and it's flaming embaressing and exhausting, plus the other friend's DC who is a good 16 month older has started being a bit mean to my DC! Urghh I just want to go for a nice drink wesring nice clothes and not have competitive talk about schools or kids or houses. I had attached of childfree friends and friends with much older children where I used to live and I missing interesting conversations in nice locations so much!
That is awful though re your friend Kurt, I wondered that re being drunk, no excuse, that would floor me too. I don't think you've anything to lose by trying to get to the bottom of it.