International Couple Searching for Long-Term Rental in Trondheim

I am an architecture student from Austria, currently participating in an international program at NTNU. My boyfriend, who recently gratuated from a Mechanical and Industrial engineering degree in France, has also moved here and is working here since September. We are currently looking for a house or an apartment to rent, preferably in the city center. But we are also open to other places with good connections to transportation. We are 26 and 24 years old and are seeking for a long-term rental, as I will be studying here for another 1.5 years. We do not have children nor pets and are non-smokers. We appreciate Norway and its beautiful nature in our spare time. Tusen takk!