Most of us are hard-wired to connect with other people. Our relationships are fundamental to who we are and how we function - in our families, our communities and in society.
But most of us are also programmed from an early age not to reveal too much about our personal lives. We learn to avoid 'over-sharing' at all costs.
That probably explains in part why so few people talk with real honesty about the impact of a brain tumour diagnosis on their personal relationships.
It's easy – and comforting - to assume that this kind of sudden and dramatic life event brings people closer together.
The reality is often much more painful and very hard to accept, let alone to admit publicly: relationships are profoundly altered by the disease and its effects.
How could it be any different, when brain tumours change people themselves?
In a survey we carried out last year, we asked people to tell us how their brain tumour diagnosis affected their relationships. Bravely, they did.
We published the results in our report, Losing Myself: the reality of life with a brain tumour.
Two thirds of people said their diagnosis had had a negative impact on their relationship with their partner, leading in some cases to separation or divorce.
Others felt they were living with a stranger, robbed of the person they chose to spend their life with.
The truth is that whether you're living with a brain tumour, or you're the partner or parent of someone who has been diagnosed with the disease, it's a tough and lonely place.
You have to learn new rules, tiptoe over eggshells, work out different ways to communicate with someone you once knew as well as yourself - and all when you may be grieving for a relationship that you feel is slipping away.
One of our commitments at The Brain Tumour Charity is to improve life today for everyone affected by a brain tumour. That's as much about relationships as it is about surgical techniques or the side-effects of chemotherapy. But unless we understand the many ways in which a brain tumour diagnosis really affects relationships, we won't get very far.
If you've been diagnosed with a brain tumour or the disease has affected someone you love, sharing your experience can help others to feel less alone.
You can also help us understand what more we can do to help the 55,000 people in the UK who are living with a brain tumour.
So if you would like to tell us how a brain tumour has changed your life, share your story. Sharers are very much welcome here.