Which one?

Interesting poem of unknown origin

One of us dear--But one--
Will sit by a bed with a marvelous fear, 
And clasp a hand growing cold as it feels for the Spirit land. 
Darling, Which one? 

One of us dear--But one--
Will stand by the other's coffin bier, 
And look and weep, while Those marble lips strange silence keep.
Darling, Which one? 

One of us dear--But one--
By an open grave will drop a tear, 
And homeward go The anguish of unshared grief to know. 
Darling, Which one? 

One of us darling, it must be.
It may be you will slip from me, 
Or perhaps my life may just be done. 
(I'm glad we do not know) Which one?

(Credited to Julia H. May in Parry's Monthly Magazine in 1887, but often printed uncredited or credited to someone else; for example Locomotive Engineer's Journal credits it to "Alice H.")