How was she tested for trich? Have either of you been in a hot tub?
This was once thought to be only sexually transmitted. This may not be the case.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4553853/
https://www.healthline.com/health/how-can-you-get-trichomoniasis-if-no-one-cheats#did-my-partner-cheat
https://www.stdcheck.com/blog/how-to-get-an-std-without-having-sex/
https://emedicine.medscape.com/article/230617-clinical - you have to sign in to see the whole thing, but the summary may be enough
It's rare to get it without sexual contact, but it is possible. It's also possible that she had a false positive test.
I'm sorry she skipped right to divorce proceedings.