In other words, since it is a name for an impure force, what does the Midrash mean to say they were married?

What does it mean to be a wife?

What does it mean to be an impure force?

Whaddaya say we learn our aleph-bet first and leave things we don't understand for people who understand them. If and when we get to that level, great!

Chava was Adam's first wife.
They had Kayin, Hevel, Sheis and many other children together.

All 100% true and we all know exactly what it means.