Can I test positive for meth after having sex with partner who uses

Unlikely...unless he literally had it ON his penis. Esp if he had it on it and you gave him oral.
BTW, if you don't use, why did you have to do UA?
Was the specimen tested in a lab or just a dip? If in a lab was it tested further for verification? Have you been in hospital and given medications? Smoked weed?
I'm a Substance Use Counselor. Yours is a story I've heard before. Did you test pos for anything else? Did use anything else? There are multiple ways you could have been positive. Do you know what the metabolite level was! Have you been taking other medications? Energy drinks? See chart below for some over the counter and prescription drugs that can produce false positives. Just remember it does not happen often.

I did test positive and don't know why know other medications I do smoke
weed that's it

I have to UA for probation.

That's probably it. Unless you raised your own weed, or bought it from a dispensary, it can contain just about anything!
So you did test positive, or you are worried that you might?
Sue

I also tested positive for Methamphetamine. I was selected for a random at work and was required to do hair folicile-urine-mouth swab. The hair came up positive for Methamphetamine Which I have never ever used in my life. I take prescription Vyvance which is Lisdexamphetamine. I was told by the DISA medical review officer that Vyvance would show up as just an amphetamine and not as Methamphetamine. Now I am suspended from my job of 10 years as a supervisor for something I did not do. My partner whom I have been with for 2 years was using (I was unaware) for the last 6 months on and off is what she told me after I came home and told her what happened. She broke down and admitted to using Methamphetamine for the last 6 months. She used by methods of snorting and putting it in her anus. We have sex every day (never snap sex though) and I believe this is how I got it in my system. I’m not sure how possible it is or if my Vyvance is showing up as Methamphetamine for some reason but if I can prove she is the reason my career is ruined I will be leaving her forever as this is a life changing event for me.

I had a positive on a random after having sex with someone who uses meth regularly but I didn't even think about it transferring any of the drugs to my system. I don't know how much it takes but it's got me grounded from driving a truck until I get through a sap program. Definitely not worth the results for a little bit of fun between the sheets