Prince Harry has not yet asked his big brother to be his best man.
Speaking with U.K. radio host Roman Kemp on Wednesday, Prince William said about being tapped for the wedding day role, “He hasn’t asked me yet, just to clear that up. It could be a sensitive subject.”
William, 35 — who earlier in the day observed robotic surgical procedures at the Royal Marsden Hospital — also said he is “still working” through the conundrum of the wedding and the soccer F.A. Cup soccer final both happening on May 19.
The subject came up during a group discussion of the Campaign Against Living Miserably (CALM), a mental health charity aimed at preventing male suicide. Former British soccer star Rio Ferdinand asked if the wedding meant that William is likely to miss the big game. William, who normally goes to the final, replied that he was “trying to see what I can do” about the situation.
CALM recently launched the “Best Man Project” to promote the idea that men do not have to wait until a wedding to prove they are a supportive friend, and to encourage them to be proactive in looking out for their mental health.
William, a passionate advocate on the subject of mental health, noted the importance of men speaking openly to one another about their emotions. He said that he and Harry had bonded through such discussions, particularly after the 1997 death of their mother, Princess Diana.
“Our relationship is closer than it’s been because of the situation we’ve been through,” he said.
“Losing our mother at a young age, it’s helped us travel through that difficult patch together. You’re like-minded. You go through similar things — it’s a bond, and it’s something you know you’ve tackled together and come out better for it.”
“That’s the thing about being a best mate, inevitably one of you is sometimes on an up, while the other is on a down. You’re always there for each other and repaying that favour.”
Of his own emotional journey following his mother’s death, he said, “Personally, I didn’t want to be a burden. So I knew that if I trapped this inside and it got worse, and inevitably I would get worse in the future and I’d be a burden to my friends and family.
“I didn’t want that for my life. I didn’t want the traumatic moment that happened to me to then affect my life for the rest of my life, and I knew my mother wouldn’t want that for me either. So I actively went around dealing with it. Talking about it.”
He added: “We’ve got to break that down where it’s okay to talk. Sons, fathers, it’s okay to have that chat. Someone’s got to be the brave one and take the first step. Say I’m putting it out there: That upset me, or that pissed me off. You’ve got to take that initial step to bring that conversation to a head.”
CALM is one of the key charity partners of Heads Together, the campaign led by The Duke and Duchess of Cambridge and Prince Harry.
The charity is particularly focused on services for men in crisis or distress, in an age where suicide is the single biggest killer of men under the age of 45 in the U.K. William was spurred to try combat male suicide as a first responder during his career as an air ambulance pilot.
This article originally appeared on PEOPLE