Romanian is very similar to Italian/Portuguese/Spanish and I think Moldovan is too (if they don't just speak Romanian) so it makes sense that they live there
Romanian isn't very similar to Italian, Spanish and Portuguese
They all have a common root: the Latin language, but 2000 of influences did some damage
They still have some similarities, though. We also have influences from the slavic languages, the 'haide' similarity with the Serbian 'ajde' being a proof
Most of the Moldavian people speak Romanian (well, there are very few differencies in the lexic, many of them being also archaic Romanian words; pronunciation is also kinda' different, sounds more like Russian; for us it's funny to hear a Moldavian speaking
). In a few regions there are many Russians and Ukraineans, so Moldavian themselves speak those languages in those parts. Well, the Russian part is called Transnistria and have an unofficial capital in Tiraspol. The largest part of Republic of Moldova was a part of Romania since forever (well, Romania was formed of 3 different principalities of the same language and origins, until modern times: Transylvania (
) (Transilvania), Wallachia (Valahia) and Moldavia (Moldova): the actual Republic of Moldova being ~ half of the last one) and has the capital in the city of Chișinău. That part of Moldavia (also called "Basserabia") was stolen by Russia ~ 200 years ago, then came back to Romania, then went back to Russia. It was part of the Soviet Union and from 1991 it's independent. Ukraine also has a part of the old Moldavia, called Bukovina.
Sorry for off-topic/historical and ethnological lesson