Hi there, I'm quite a newcomer to the Netherlands, but I think you'd have some luck organizing trips to Christmas markets right now. I've seen some other expat groups organizing trips by train to Cologne, and Brussels also has quite a lovely Christmas market.
Some other options might be to choose a restaurant and see if you can get a small group to commit and make reservations. Movies, improv nights, music concerts...
The thing is finding where and when these things happen.