But she wasn't
"attempting suicide." By definition, attempting suicide means taking an action that you expect
will result in your probable or certain death. Lois was so confident of her conclusion that Clark was Superman -- which, again, was absolutely correct
-- that she did not consider herself to be in any significant danger. She considered the risk of death to be low enough that it was worth taking that risk to achieve her goal. Which, as a survey of Lois Lane's career on screen and page will demonstrate, is something she does as a matter of routine.
Sure, as I said, she miscalculated about Clark's ingenuity at hiding his identity -- but she did not
miscalculate about the level of danger she was in by jumping out that window, namely, none.