Tbh I’m really not sure why people make such a big deal out of Alfie not having proposed to Zoe yet. He’s only 27, which these days is quite young to get married. Me and my friends are in our late 20s / early 30s and many have been with our partners since university (i.e. 8-10 years) and proposals are only now beginning to be a thing. For me a wedding is quite a grown up thing, I definitely wouldn’t want to do it before I’m 30 lol, but I guess it’s down to personal preference.
With that said, for me it’s clear that he’s completely lost interest in Zoe, in fact they seem to be fed up with each other. And it’s not because he hasn’t “formally” committed to her, it’s because their relationship has run it’s course and they’re both miserable in it. I find that way more depressing and sad to see than her not having a ring on her finger yet. Also I guess it sucks if he’s doing it for the wrong reasons (aka his parents) but ultimately it’s perfectly possible to have a great relationship without getting married - though Z and A definitely ain’t it