Thank you both for your responses. You mention some very familiar effects. My partner seems to have got addicted when prescribed drugs for a foot injury, She often seems cold in personality... to the point that her lack of empathy / sympathy is quite astounding. Not judging, just want to make things better. Thank you. I'll gather more info.
An addict will lie about their addiction as CBF says.
Others effects you might have seen are wild mood-swings, lack of empathy, lack of other emotions, loss of sex drive, depression, pointless anger, poor decision making and memory problems.
I've seen this from both sides and can say it is very difficult to have a successful relationship with an addict in denial, the addiction is more important to them than anything or anyone else sadly. If your partner is regularly taking any opioid they will be dependant on it, regardless of what they might say...
Well from being on the abusing end I can tell you that it really ruins trust between you because there is usually a lot of lying that goes on to ones partner. I should say in my case anyway. When using I will lie through my teeth to not have my codeine thrown away and usually they are stupid lies that I always end up getting caught in. As you can see, my log in name is changing best friends because the drugs end up being your best friend after awhile. You spend so much time trying to make sure that you have your next script, etc. that it is always first in your life. Anyway, good luck to you. I wish you the best and I hope it works for you. Why do you think that your partner abuses codeine? Have you noticed that they take too much or what makes you ask the question?