I don’t think infertility is the case. I think it became clear at the beginning of this year based on things Zoe said that they had decided this (2020) would be their ‘fun’ year of travel and whatnot and in 2021 they would try to have kids. For a woman who has wanted children for years and in a very long term relationship and used to talk about the fun of being ‘young parents’ and now over 30 and having been told no wedding but we can have kids I guess, I’d imagine that‘s as far as you could push her to wait... likely having her first baby around 32.
For Alfie, future with Zoe has always been in the vague hypothetical, the way that high school kids talk about marrying their high school gf/bf someday. Everything is always off in the future and far enough away that you just talk about it in the sense of ‘what would we name our kids lolol’ and not anything real. But I think he agreed to ‘year after next’ finally and had planned to have a crazy 2020 which he probably thought would make him feel ready.
I know we can’t tell just from vlogs or whatever, but I don't have the sense that they have been in the space where they’ve been actively trying to start a family for a while now.
I think the question is, if this guess based on things Zoe was saying is correct, will COVID push them away from that agreement or timeline? Will Alfie want one more year, etc.