By a happy coincidence , we arrived at exactly the same time.

碰巧运气好，我们刚好同时到达。

《牛津词典》

Ours, by a happy coincidence, seem always to be just right.

BBC: Fed gives itself a new target

Last month he dispensed the man-of-the-match award at Sri Lanka's opening game of the cricket world cup, which took place in a newly built stadium in by happy coincidence his own constituency, Hambantota, in the south of the country.

ECONOMIST: Sri Lanka: The son also rises | The