TL;DR: A colleague invited me and my wife to a dinner and we don't want to go. How to politely decline?
I have a colleague that sometime works on the same project as I do. When he does, he often comes to me with detailed questions regarding his work, basically asking about each step he should take, to the point it would be easier for me to actually do his work than to explain every step to him.
At first I helped him with his inquiries, but recently I became more assertive and I told him something along the lines that he should first try to solve the problems himself before asking for help.
A few days ago, he invited me and my wife to a dinner. It was quite surprising, because we don't really talk much (other than work related stuff), and we both have other people at work that we tend to hang out with. Anyway, I declined because we had other plans on the date he suggested.
Today he invited us again (over phone). I don't know what his thought process is, but me and my wife feel quite awkward about it, and we would prefer not to go. How can I politely deal with the situation?
(The colleague is Canadian, working in an European company. We are both the same seniority.)