The points distribution is different when you're single vs when you're married/common law.
https://www.canada.ca/en/immigratio...iteria-comprehensive-ranking-system/grid.html
For example, if you apply on your own, you can get up to 150 points for education (if you have a PhD for example). But if you apply as a couple, the main applicant gets a maximum of 140 points and you can get 10 additional points for the spouse's education.
Language is another example. You can get a maximum of 136 pts for language if applying on your own, and a maximum of 128 points for the main applicant if applying with a couple + a maximum of 20 points for the couple.
So based on the information you provided, not having an English test for your partner is one of the reason why your score went lower.