In Hamlet, what does the player mean when he says "What to ourselves in passion we propose" in III.ii?

This quote comes in the middle of the lengthy conversation
between the player King and the player Queen. They are playing The Murder of
Gonzago, also referred to as The Mousetrap by Hamlet.
The couple are discussing the possibility of the queen moving on to a second marriage
upon her husband's death, as the King feels he is dying, or at least getting old enough
to know that death is not out of the question. Directly before the King's speech, the
queen says:

readability="13">

The instance that second marriage
move

Are base respects of thrift, but none of
love:

A second time I kill my husband
dead,

When second husband kisses me in
bed.

This passage serves to
hit the real King and Queen in their hearts, as Queen Gertrude has done exactly what
player Queen says she will not do - remarry.

The player
King protests saying that the passion will grow old and weak and eventually, she will
change her mind, because life dictates so. When he says "What to ourselves in passion we
propose,/the passion ending, doth the purpose lose," he's telling her that it's only the
"passion" she feels at the thought of his death that is making her say she will never
marry. Once she gets over it and a little time passes, she will think differently and
will probably marry someone else. This is meant to be similar to what actually happens
with Gertrude and Claudius, after King Hamlet is killed.