How do I help someone in mourning?

One of the most important things is talking it out. Although getting into the conversation and most of the actual talking will be super awkward you just need to let him vent. Another really important thing is that you let him know that it's okay to be upset. I lost my grandfather who I was really close to exactly a year ago in like 3 days and what helps the most is letting things out. Let him cry to you. Let him tell you about how he feels. Let him know that he can trust you with anything. Eventually the pain will get lesser and lesser and you will both come out of the experience closer than before.

It's important to understand that when you lose someone, the pain never really goes away. The pain becomes a small part of you. Of course, you can eventually enjoy life again, but you are always going to feel a little bit of sadness in your heart. So I'd advise not adressing your boyfriend with the idea of 'It will get better'. It may take a long time. And I can guarantee that the conversations you guys will have will probably be really redundant on his part. But it is important he talks it out, the good and the bad memories. Refrain from analyzing what he says, and instead listen with compassion. Of course, Remind him that you care and you are there for him. Also remind him to take care of himself as well.

My best friend's dad just died and I was in the exact same situation. Basically all people need is to not feel alone, so just be there with him, hold his hand, hug, let him know you're there to listen. What I did was just watch loads of funny movies so my friend was preoccupied and cheered up for a bit :) Hope this helps

Talk about it with him... Do fun stuff together to help ease his mind.. I lost a very close loved one and the #1 thing that helped me was people just saying very very nice things

When I lost my father what helped most was people who didn't feel sorry for me and didn't pry. I accepted condolences, but mostly what I needed was just friendship and normality from my loved ones. Nothing is ever the same once you lose someone close, but just continuing to receive love and support, without a sense of pity or "poor you", is probably the most one can do to help you feel better. It's wise that you feel uncertain of how to react, it shows you care. Death is one of those things that kind of just... stops... things. But if you talk to him, I'm sure he'll explain that he's happy you care about him, and that he's lucky to have you :) Just by showing your love you're helping immensely, I assure you :)

@Alvana there's so much wisdom in your words.
A year ago we lost my 10 year old nephew and the grieving has been terrible as it always happens when it's a kid who has to go. I've lost most of my friends because most people just don't know how to handle it. All I needed was for them to listen but even that sometimes is a lot to ask. A lot of my friends were parents and they just couldn't take in the idea of it happening to them. At times I wanted to be distracted and have fun, at others I wanted to cry and have someone holding me, and those two things could happen within a couple of hours. It's just a roller coaster of emotions. If you really want to help, just be there and try to do whatever it is he wants to do at that moment. Maybe it won't feel like you doing much, but all in all, when he looks back he will know that you were there for him.