So ureaplasma isn't really considered an STI as such. It can live in normal, healthy urinary tracts with no issues. Sometimes they "over grow" which can cause symptoms similar to NSU/NGU. People can have this for years and year with no symptoms so it cant be used as a sign of cheating.
What made him test? It is a very specific test and is not part of a normal STI test kit.
me and my boy friend where separating due to my parents caste issues . so he gave idea to take both STD /STI premium test . And he got it and i got also may get i am afraid , Since we had continues 3 years sex .