You're in luck
I had the SAME situation a few years back with my ex.
Very lazy person, never wanted to go out if it was too hot or too rainy. It really had me trippin every single time. But one day as I was just staring at the ceiling, unhappy, I just said **** it.
The next time she told me she didn't feel like it, I told her I was gonna go chill with some other people instead. She said "Ok thats cool......who?" I mentioned a few guy friends and a lot more girls, and I said they were all going out and had wanted me to come along but I said no because I wanted to spend the day with her instead. It was a fib, yes, but it put her in line because one of the girls I mentioned, she HATED.
She indirectly asked me not to go, and to "stay home and be with her" but I said no, I don't want to stay home today, I need to go out. I called up my buddies and some girls and had a GREAT TIME