Spying on @philh writing his 200 words, I noticed that he was replying to your post, and I immediately jumped to read it as well.
For me the trigger to respond was the sentence referring to relationships being lenses thru which our lives might seem... less insignificant. (Reading Philippe's post later on I pondered, how completely different things people resonate to.)
I wholeheartedly agree with your statement, but, as I often do, I wanted to find some "scientific confirmation". I threw "life", "meaning" and "relationship" into Google search and opened an article Secret Meaningful Life Meaningful Relationships on The Gottman Institute blog website. It did provide what I was looking for! A couple of clinical psychologists, Drs. John and Julie Gottman express the very same opinion, yet they base it on results of over 40 years of research.
(...) most significant sources of meaning in life are, perhaps unsurprisingly, close relationships.
Just as you listed, these would be relationships with a partner, children, friends, yet, in their study, one of the findings surprised them, and me consequently.
"Loose ties to others can also be a potent sources of meaning".
The crucial sense of belonging can be achieved by cultivating contacts with... cashier in supermarket, bearded barista, even a stranger on the bus stop, or friend just out of jail. (Yeah, I just discovered that you guys keep on dialoguing makes me feel a bit like a third wheel of a bike here now.)
"These micro-connections are sources of meaning we can all tap into to lead deeper and richer lives".
Isn't that wonderful?!