I need help settling a debate between me and my wife. She says it is a weed and I'm saying its not. Who is correct? This grass looks very soft and grows in clusters too.
If you didn't plant ornamental grasses, then both the grasses are just grass. A 'weed' is just a plant growing where you don't want it, but I'd consider this grass as a 'weed'.
Unless you've grown plants that seed themselves, generally, anything that pops up unbidden in unoccupied soil (unless it's something like a perennial or bulb you've forgotten you planted) is most likely a 'weed'.
I am guessing Fescue
The trick is to get to those baby weeds while they are babies. Hula hoe works beautifully. Rips up baby plants and that is all it takes. I clean out the trenches between my lawns and beds and dump that soil on top of those baby plants. Or use Gro-Co, mulch for ornamental plant beds...no weed seeds, no pesticide residues, completely decomposed and ready for the soil organisms to consume...Seattle area only that I am aware.
Weeds are my absolute last worry in my gardens, even gardens of properties under maintenance contracts. Weeds are too easy to control and although I was licensed as a Commercial Pesticide Applicator, they taught us how not to need to use pesticides. Pesticides are a bandaid on a problem we should have known about. We made the problem. All soils are full of seeds. Not talking about potting soil. If one blocks out the light to weed seeds, doesn't water shallowly and frequently and makes sure to cut them down during infancy as a seedling way before they go to seed, there will not be weed problems. Weeds are not super natural plants. Just survivors. People think that a little seedling will regenerate from a root. Not happening. Perhaps established perennials like crab grass or Equisetum, but there are few plants that grow from a segment of root.
For argument or debate purposes, grins, that top pic that might be a fescue grass is sold for 10 bucks a gallon potted plant.