Yes, trichomonas infection can be present without symptoms ("dormant") for many years, in men, women, or both. Your infection does not imply that you or your partner has cheated; you might have been infected for years, or perhaps your partner had it without symptoms and brought it into the relationship. As I said, you'll probably never know exactly when you were infected and you'll go crazy if you keep trying. I strongly recommend you stop trying to figure it out.
Welcome to the STD forum.
The standard treatment for trichomonas is a single dose of metronidazole (the most common trade name is Flagyl). It is only about 90% effective -- in other words, persistent infection occurs in one in 10 treated women. The recommended management in such cases is a longer course of either metronidazole (e.g. 500 mg 3 times daily for 5-7 days) or a few days treatment with tinidazole (Tindamax). In addition, your current partner needs to be treated, even if asymptomatic. Since you might have a slightly resistant strain, it would be reasonable for him to also receive several days of metronidazole or tinidazole, instead of a single dose. But these treatments should take care of it.
As to when you originally were infected with trich, it is really impossible to know. It could even have been well before November 2009.
Discuss this with your NP and let me know if you have any further questions. But don't let this bother you much. Trich is an inconvenience, not a serious health threat -- and it will clear up with more intensive treatment.
Happy new year-- HHH, MD
A related discussion,
long term relationship was started.
Because I am extremely upset about this, I do have another question(s). How is it possible for me to have gone so long with no symptoms? Can this parasite be dormant for months or years? I just want to be sure because as I said above, I have no reason to suspect my partner of cheating (kinda was hoping he was The ONE). I hope he has no reason to suspect me of cheating as well. Is there any research out there I can find out there to prove my case if I have to?