What options are available for a couple who want to stay together, but only one needs assistance with ADLs?

Where my mother lives (in Arlington Heights - a NW suburb of Chicago), you can get as much assistance as you need in an independent living apartment. They have three different (at last count) home healthcare agencies with offices in the building that can come in and do bathing, dressing, cooking, etc.

I just have them come in 2X a day to give my mom meds. But I could have additional help all the way up to a 24/7 caregiver in her apartment. So yes, those kinds of support are available.

Sure they exist. The definition of 'assisted living' varies by region and provider. Make a list of ALs in the area you prefer and call each one and ask what services they provide. You can also consider hiring aides, either per shift or as a live in. The ALs in my area would not allow live in so you would be hiring by shift and that is typically more costly. You might look at continuing care communities and investigate the independent side. The cost might be lower and the excess could be used to buy the services of an aide. There are series of 'regional lists' of places for adults and seniors to consider. Look around or call your county office of aging for ideas. I saw many folks stay in the independent side of the house in my Mom's continuing care community. They had full time live in aides that provided help with the ADLs. You can also use the boxes on this site to provide a starting list. Good luck