Have you ever not used a name because you prefer the opposite sex version

[MadamePeacock]

My friend is having a little girl. She was all set on Oliver for a boy and Olivia for a girl. She loves Oliver more than Olivia and now she is having a girl, isn't sure she wants to use Olivia in case she has a boy in the future. She can't find another girls name she likes as much as Olivia but still wants an Oliver in the future.

Has anybody else done this??

I haven't, but I would I think.

I love the name Rowan, but would rather use it for a girl than a boy so would probably hold off on using it for a boy incase a girl came along in the future.

Tough one, but she might never have a boy and regret not calling her daughter Olivia. Or she might decide she prefers another name to Oliver by the time she has a boy. I would always make the decision based on the name we like best for the baby we're actually having. I wouldn't use up first names I love on middle names, though, I'd save them just in case!

She may never have a boy. I'd use the name for the baby that's here now (or imminently) and cross the boy bridge if it came to it.

I haven't personally, but I get where your friend is coming from.
Eg Most unisex names. I like on girls rather than boys.
I love Robyn and Taylor for girls, but hate them on boys. Although Roby(i)n and Taylor where originally used as boys names.

She must know if they're planning a second/third/fourth child though.

If she has a boy then he can be Oliver and if the last one is a girl then she can use Olivia for that girl knowing that a boy isn't on the cards.

Just because they plan to have more children doesn't mean they definitely will, they might not be able to have more, or they might just change their mind.

I think it's weird to save your favourite name for a hypothetical child instead of giving it to your actual child.

Ironically not a big fan of the names Oliver or Olivia myself, but that's not the point!