Is it allowed to ejaculate between your wife's buttocks and outside her anus?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

There is no harm in that as long as you avoid having sex in the anus.

For more benefit, please refer to Fataawa 107052, 90032, 86457, 87038 and 85937.

Allaah Knows best.