In love with my dead friend’s husband

I lost one of my friends some years ago though we were not really close. I’d always liked her husband and was a friend. After the wife died, we started dating and became lovers.

Now he says he can’t really put his mind into our relationship, that it’s too soon after his wife’s death and he still misses her. We still flirt and fond of each other, but no love making. How long should you mourn a dead spouse for goodness sake?

I love him and he’s grieved for four years. Surely, he should be ready to move on?