I don't think this is relevant @Mila14 but just in case it is I am sharing.
Your phrase we both thought we would die of sadness reminded me of the time I split from the one boyfriend I had really loved and 'got me' the split was due to his dark side, his drug/alcohol use and mismatched lifestyles (I was starting out as a jet set career girl he was partying). I honestly thought I'd never stop crying.
A few years later after I'd moved to London and dated a load of guys that didn't compare in beauty, humour, beauty, cleverness etc we reconnected due to a chance meeting at a festival. It was brill. We ended up marrying and he is now my bad XH father to my three damaged kids.
That dark side turned into dire depressive (and narcissistic i now realise) mental health and his drinking never stopped. He restarted recreational drugs when he fell in with new crowd.
My deep love for him helped me not see how crap he was. Twenty years later after reconnecting I binned him after one terrible night where he brutally attacked our weedy 15 son.
Soooooo. I've got no idea what lessons are to be learned.
I often say to blokes on OLD who say 'how are you finding this dating malarkey?' that I love it hugely and if only it had been invented in 1998 I might have found a better candidate husband/partner than my now XH offered.