Input on things?

So I'm engaged and my other half has a guy coming around to talk to him about starting a plumbing course, his mom and dad are also here but they told me to go upstairs as I don't have any right of opinion in the course as its to do with my other half and them ..
Do I have a right to put my input or not? 
Personally I feel unimportant that I'm not involved & my other half didn't even back me up..