Is it weird that I still check on my late girlfriend’s mom?

I don’t really know who to ask about this, so I’m asking here. My girlfriend passed a little over three years ago. Hereditary heart condition. Very sudden. After something like that, a lot of things don’t really get a clean ending. I work in Atlanta now, but home isn’t that far, so I get back about once a month. I see my parents, and I usually stop by her mom’s too. Her younger sister is still around. Sometimes it’s the three of us getting dinner or running errands. It’s not always some heavy grief thing. Sometimes it’s Costco, fixing a door handle, sitting in the kitchen for a bit. Her mom lives alone. She says she’s fine, but over the last year her hearing has gotten worse. TV loud, missing things from the other room, laughing along at dinner when I know she didn’t catch it. A little while back her sister came up to Atlanta and I took them to Costco. We were mostly there for regular house stuff, but we ended up looking at hearing aids too. Her mom kept saying she wasn’t “there yet.” Her sister said, “Mama, you’ve been saying that for ten years.” She uses AirPods sometimes now, mostly at home or for calls. I also got her a vivtone supermini because she didn’t want something big on her ear. She seems more willing to wear that one when she goes out. Not every day. Just church sometimes, groceries, dinner out. Last time we ate out, the waitress asked if she wanted a refill and she answered before I could repeat it. She looked over at me like she was embarrassed I noticed. I didn’t say anything. Dropped her off later and sat in my truck for a minute. I don’t know. I’m not her son. She’s not my mom. Her sister has her own life, and I have mine. But not checking on them at all feels cold. Does this sound weird from the outside? Am I doing a normal decent thing, or am I keeping myself stuck?