I thought yucca at first but its taller than the yucca I've seen, and doesn't flower. It multiplies pretty crazy also. It's taken over this corner, and it will hurt you if you aren't careful around it.
With 49 species of Yucca an ID would be a shot in the dark. By your description of not flowering Y. filamentosa is off the table 48 to go. Perhaps a Yucca with a long bloom interval. Jerry
I am also going to throw out Cordyline australis, as mine has multiple starts like yours. And if that is a flower stalk in the back it looks similar to mine when it bloomed. Probably a variety of yucca though.
It may be a yucca, I'm still sceptical about it though. These plants also don't have the fibers I always see curling off of yucca leaves. I've been looking at various types and they all seem to have these fibers. This plant looks like a yucca from afar, but it's different when you take these details into account.