I'm lucky in that my girlfriend can take class when I'm teaching and we are just instructor and student. Again, this is very lucky as I've usually seen it not work out like this. In my tai chi days some members of my family came to class and we just couldn't work together. The instructor actually instituted the "family doesn't work together" rule because of it
It can work. There are many examples both ways. My sensei is married to the senior student in our dojo. They've worked it out so it's not a problem. The senior student of my class is an ikkyu and his father is a rokkyu. There is no friction when the son is teaching class and his father is just another student. So, it can work it just really depends on the mind sets of the involved people.
p.s. No way to know until you try