There’s an Episcopal icon-writer who has an icon of St. Gregory of Nyssa and St. Theosebia (“a deacon”), and says they were a married couple and a liturgical team.
First off, St. Theosebia was St. Gregory of Nyssa’s biological sister. Orthodox tradition says so, Catholic tradition says so, and only a few recent historians and theologians have interpreted the evidence in any other way.
Secondly, we don’t actually know if she was a deaconess or not, except that tradition does say she was. All we know from the materials is that she helped out St. Gregory and the Church. Since she is specifically called “support of women” and “hope of women” in various materials, she probably was a deaconess ministering to women. She may also have been the founder or leader of a “choir of virgins” that St. Gregory of Nyssa talks about elsewhere. So you can’t have it both ways. If you believe Eastern tradition about her being a deaconess, you need to believe it about her being the man’s sister.
The trouble seems to be that St. Gregory of Nazianzus’ consolation letter to St. Gregory of Nyssa, on the occasion of St. Theosebia’s death, identifies Theosebia as the yoke-partner (“syzygon”) of a priest (ie, of St. Greg of Nyssa). But this seems to be a running joke, because earlier, St. Gregory of Nazianzus also wrote an epigram (Epigram 161) that also talks about Theosebia being the yoke-partner of a priest (“hieros syzygon”). Then Epigram 164 is an actual epitaph for St. Theosebia, where he talks about St. Gregory of Nyssa’s mom, St. Emmelia, having a daughter who was the yoke-partner (“syzyge”) of St. Gregory of Nyssa!
The quotes are probably more of a joking references to Philippians 4:3 than anything.
Here’s the translation of Epigram 164:
“And you, Theosebia,
child of noble Emmelia,
and in truth yoke-partner of great Gregory,
lie here in holy soil,
O support of pious women.
At a seasonable age,
you departed this life.”
It was totally okay for a priest or bishop to live with a sister. Given that St. Gregory of Nyssa at one point lost his vocation and became a secular rhetoric teacher, she probably helped keep him on track as well as helping his work.
Possibly St. Gregory of Nyssa did get married during his secular period, but we don’t actually know that.
Theosebia’s name means “fear of God, reverence, piety.”