Ive been playing for close to 70 hours, and was of the mind to romance Danse. I have read the walk throughs and have been doing the things he approves of but here is my issue :

I got the first flirt and passed it, however when the second one came about, I failed it. This was about 20 hours into my game and I can't go back that far.

Am I screwed, guys? Do I not get to tap that soldier booty?? Is there a way to get the converation to happen again?

the flirt options do not matter at all. the ONLY option that matters is teh romance option at the last dialogue with the companion, fail that, and no way of repeating it.

My character failed both flirt options with Piper, but was still able to romance her at the end (not that it changed much, but...)

Aye, you'll be fine.

Just do a Quicksave before you hit the actual 'Romance' button if you want to give it a little insurance.

Just to note, you won't get this final check until you reach a certain point in the main storyline. I didn't realize this, so I was really confused as to why my relationship with him wouldn't progress any further.

No stop all the Mis information. You'll be able to retry if you dismiss them and leave them in base for awhile then go back to pick them up and you'll get another shot