They have no control unfortunately or else I don't think they would want to do that. But grief is also a really hard thing to deal with so I do understand if someone dangles that in front of you it's hard to resist.

[Considering he himself went for it but survived. All he ended up getting was a scar over his left eye and white hair from the shock of what happened.]

For me it is because I see how they are feeling and depending on level they are always crying.

But yes the use of my powers does because... I guess I will say it like this. It puts more pressure or strain on those who have the innocence infused with their body and thats why they have shortened life spans. Weapon types don't have that issue and thus they would if they aren't killed in the fight typically would live longer.