" It's not like" means it is not the case, or it is not true that we're sneaking around behind her back.

“不像” 就是说不是这样， 或者说我们在她背后偷偷摸摸是不对的。

It is not the case, almost certainly – maybe there are some exceptions – but it is not the case that people choose their sexual orientation.

情况并非如此, 几乎可以肯定▁-▁也许有一些例外▁-▁但人们选择性取向的情况并非如此。

But if this sort of interest is included, it is not the case that matter has no importance for us, provided it exists even if we cannot know that it exists.

但是，如果包括这种利益， 那么物质对我们来说并不重要， 只要它存在， 即使我们无法知道它的存在。