Rationality and Morality of Suicide

Consent
You cannot kill yourself against your own will, you gain consent for this action, like actions such as in the doctor case. Like hitting each other is not alright without consent, yet boxing is presumably morally acceptable. Under the criteria of consent, suicide is permissible if we have no other considerations. This makes all suicides moral.
Maybe we should not go this far with consent- if someone asks to be killed, should we do it? It doesn’t seem morally acceptable. What if you are not competent to make a rational choice, what if like ultimate slavery or suicide, it is irrevocable?
This is missing the previous point about the rationality of suicide.
What if a hand grenade is thrown near 5 soldiers and you don’t have time to warn them, but you can save them by throwing yourself on the grenade and thus killing yourself, but saving them. Would this not be a moral action? Why is this okay- it’s because it is consensual, unlike throwing someone else on the grenade.
What are the relevant conditions for consent to determine morality?
Free/ informed/ sanity/ competent/ etc.
Under these criteria, there seem to be situations where suicide could be moral on the basis of consent.

CONCLUSION
Whatever criteria we use, suicide seems to be in some cases both rational and moral. So the question is- how should we act when we come across the situation of someone trying to kill themselves?
Perhaps, we should consider that consent is not always the case and err on the side of caution. To accept that is not the same as to accept the stronger conclusion that one should never kill themselves.
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