For over 80 years, Harvard's Grant and Glueck study (https://news.harvard.edu/gazette/story/2017/04/over-nearly-80-years-harvard-study-has-been-showing-how-to-live-a-healthy-and-happy-life/) tracked the physical and emotional well-being of two populations: 456 poor men growing up in Boston from 1939 to 2014 (the Grant Study), and 268 male graduates from Harvard's classes of 1939-1944 (the Glueck study).
They diligently analyzed blood samples, conducted brain scans (once they became available), and pored over self-reported surveys, as well as actual interactions with these men, to compile the findings.
The data is also very clear that those who feel lonely are more likely to see their physical health decline earlier and die younger.
In another study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4579537/), researchers found that women who felt securely attached to their partners were less depressed and happier in their relationships two-and-a-half years later, and also had better memory functions than those with frequent marital conflicts.
Inc.com writes: This is a very good reminder to prioritize not only connection but your own capacity to process emotions and stress. If you're struggling, join a support group. Invest in a workshop. Get a grief counselor. Take personal growth seriously so you are available for connection.
Specifically, the study demonstrates that having someone to rely on helps your nervous system relax, helps your brain stay healthier for longer, and reduces both emotional as well as physical pain.
It's the quality of the relationships--how much vulnerability and depth exists within them; how safe you feel sharing with one another; the extent to which you can relax and be seen for who you truly are, and truly see another.
According to George Vaillant, the Harvard psychiatrist who directed the study from 1972 to 2004, there are two foundational elements to this: "One is love. The other is finding a way of coping with life that does not push love away."
The data is clear; in the end, you could have all the money you've ever wanted, a successful career, and be in good physical health, but without loving relationships, you won't be happy.