Yes. Not just with my other half but with people in general. It makes me feel a bit phony at times! Like I'm pretending to be happy when I'm not.
I think sometimes though it's a fear that people won't be able to accept your emotions (well it is for me!) I was always told I was too sensitive. So now I hold things in when I'm upset. Even when people have passed away I find it hard to cry or show any emotion.

I feel embarrassed if people think I'm not holding it together.
So you're definitely not alone! I think in a way most people will do this to some extent, but I think we need a select few we can be open and honest with even when things aren't going so well.