I remember years back when I was a young mom and teacher working with a veteran teacher similar to my age now. That veteran teacher, not unlike me, was totally passionate about her work--she couldn't get enough. At that time, I wondered how she could give her teaching so much time as I was busy as could be setting up a home, getting used to parents, and active with a large number of personal events. Now years later I fully understand where she was at--it was a time in her life when she, like me, enjoyed the quiet work of developing her craft, enjoying her home, and spending time with family.
That teacher, however, was dismayed at my lack of similar investment at the time. She couldn't understand why I wasn't doing what she was doing. I knew she had never worked as a young mom so I understood that she didn't fully understand what it was like to raise a young family, take care of a home, spend time with the extended family and teach too so I didn't worry to much.
I tell this story because we all have to be mindful that we're at different places at different times. Sometimes we have a lot to give at home, in the neighborhood or community or at work and other times we have less interest and less time and energy to give. That's simply the way life is. So rather than looking down on someone's chosen time and commitment, be mindful that the individual is choosing what's best for his/her personal life and career, and that like you, his/her commitments and how they spend their time will likely change.