Jess, there have been different times in life (and probably more that lies ahead..depending who outlives the other), where I've been alone on statutory holidays. (ie. Thanksgiving, etc.)

It is harder in the winter compared to summer when I love being outdoors on the bike and don't care if I'm cycling alone (because I do cycle alone part of the time, even when we living with one another. Our personal schedules just doesn't always jive.)

Even wishing 1-2 close (unattached) female friends by phone/Skype would be appreciated by them (and you) and it doesn't have to be on Christmas Day. That's what I would do, probably before Christmas in case they are going off to visit family.

I would/have:
*prepare a lovely meal for myself
*earlier during the day, probably gone off to nice cafe or to an indoor market to have something
*play some music, etc.

I have a large family ...thousands of kms. away who always hope to speak with me. ...every Christmas Eve or Christmas Day.

This is what happens/will continue to happen. It helps alot to have several single, unattached close female friends (and several in my age range who I've known for several decades).

Would I volunteer at a soup kitchen? I dunno. In the past, the volunteer work I've done has been several days/weeks before Christmas Day itself and the organization was doing a fundraiser, event for the public.