Not wanting to date a woman simply because she is a single mother is okay.
This may get a lot of backlash but think about it. If you were to ask any single mother who the #1 person in her life is, she would, without a doubt, say her child/children. And you would never take that #1 spot. I am looking for my #1, not my #2.
EDIT: A lot of people are saying this isn’t an unpopular opinion but I catch a lot of flak for this stance.
I also dont believe this preference is equal to someone who decides not to date someone based on height.