strohl talks about how he feels like he failed will for not going by his side when will has been with him when he needed it (follower events) and he feels like he's making the same mistakes he did during halia's fall (bro you were a kid back then wtf would you have done)
and then heismay talks about how he regrets not being with his son when he needed him most so he understand what strohl feels, but the difference right now is that the two of them are alive (strohl and will) and if strohl doesn't know what to say then it's okay to just be honest with him
"regret only happens when it's too late. it's still too early for you"