My (20F) bf (20M) and I feel more like roommates than romantic partners. How do we bring the romance back?

We have been dating for almost 3 years. At the start of the relationship we were extremely close, practically inseparable. His mother was an insane mama's boy which caused severe issues in our relationship with lots of lies and constant fighting, but these issues were eventually solved a few months ago. We thought that this was the cause of our relationship feeling loveless, but even though this issue has been fixed we still do not feel closeness or happiness and still fight a lot. We are long distance 3 months out of the year due to school which puts a strain on things, and we also haven't been intimate in a long time. We've tried going places and doing things more often to try to get closer, and although we have a good time, we still end up feeling like just good friends having a fun time during these moments and the romance isn't there. How do we bring the romance back? We both say we feel unhappy and like the relationship is lacking love but neither of us know exactly what we need or what a loving relationship between us would look like. We have small "happy" moments but they don't really outweigh the arguments but I don't want to give up on the relationship.

Every few months we have a huge argument where one of us tries to break up with the other and tells the other how they're super unhappy and don't even see the relationship as fixable, along with a bunch of other hurtful words. After these arguments where the other person begs them not to leave, the person threatening to leave apologizes and says they didn't mean most of what they said. It feels like an endless cycle that could be fixed if we bring back the romance to make everyone happy.

TLDR: How does one bring back romance in a loveless relationship?