There is no point in asking about it UNTILL you know that she is.
IF she is not its lose lose lose for you to ask.
If she is and you know, its simply confirmation, and a test of her honesty. Though as Lil pointed out lots of time people love to unload the pressure cooker of guilt.

About the bench, its finished. Its a nice gesture. Dont make a big deal about it, or expect a n y t h i n g in return. Not even a kind word. Giving her the gift is another opportunity to observe her reaction. When she returns home approach her normally to give her a greeting kiss, etc. If she is aloof or offers you her cheek, peck it and then detach. Do not be hesitant or grasping.

Nop is very busy and doesnt always have time to explain the whys of his reasons. Besides a lot of this is understanding/feeling/getting the whys for yourself.
His advise is not always something the recipient is capable of doing, but it is not ever wrong advice. IMhO.

Stop listening to Dido/White flag. your W will not respect you for going down with the ship of your M. however if your Musical taste is as eclectic as it appears to be so far, please feel free to post your playlists. Im always on the lookout for differant and 'new to me'. I really miss CSW's music threads.