but my fiancee is trying to steal it.
It will be theirs once you marry anyway. Don't worry, you'll get used to it.
I supplemented my 128gb MacBook Air 11 with a 128gb Lexar S45 micro USB drive. I leave it in at all times, it's so small, I hardly know it's there. Pics and music get stored on the Lexar, leaving plenty of room on the internal SSD.
Went Lexar route because of heat issues with the Sandisk variations(First hand experience, plenty of info if you choose to google). Lexar's stay cool as a cucumber. Both drives are 3.0 smoking fast(literally for the Sandisk).
I think I paid 34 dollars for the Lexar when it was on sale at Bestbuy.
Best