To show emotion or not show emotion- this is the question

Can I get some thoughts please step parent team, Im a SM of my step daughter who is 14. Her mum, not in our lives at all last 5 years. Im infertile and don’t have any other babies. So the dear thing has me as the example of being a woman in life. Whats the go these days with showing frustration, sadness and the more types of emotion people tend to consider as negative? Im an emotional person and come from a background thats quite expressive so if the internet doesn’t work (again), I may show frustration (ie sighing and maybe a curse word or two) or sadness if Im watching something say on tv ie gaza. My partner tells me I should not be exhibiting this in front of her, it will affect her mood and brings down the mood of the house. However, does this not setup a false image on my behalf and also make her feel like as an older adult she needs to shrink her emotions and only show nothing externally unless its happiness 24/7. Or perhaps the way I grew up was wrong. I liked that from my parents, I like the passion they show for both things they did not like and equally with what they loved.