With widely differing views about what the future relationship should look like, plenty of tough negotiations still lie ahead
Breaking up is hard to do but what type of relationship will the EU and UK have after Brexit?
The European Parliament gave the green light on Wednesday to an association agreement, but the man negotiating for the parliament made clear that the UK will not have its cake and eat it.
"It is impossible to be outside the European Union and to have a better position than as a member of the European Union. That cannot happen," the European Parliament's Brexit negotiator Guy Verhofstadt told Euronews.
"We are saying the best way forward should be that they stay in the Single Market or in a Customs Union. Unfortunately, they don't want to, so let's make now a special assocation agreement not only on trade but also on other issues because they stay a close partner."
At next week's EU summit, Brexit negotiators will be zeroing in on a transition period which could effectively keep the UK in the Customs Union and Single Market for two more years.
UKIP MEP and former party leader Nigel Farage finds that outrageous.
"The trade war, or dispute with America, actually proves this," Farage told Euronews.
"We're stuck inside a Customs Union. If we go for transition, we stay inside a Customs Union. The United Kingdom could do a deal on aluminium and steel within 48 hours. So I think the time has come for the prime minister to say: "Look, we actually need to make 29 March next year the day we leave and that's it.'"
Other sticking points will be avoiding a hard border in Ireland, as well as securing citizens' rights.
Prime Minister Theresa May says Britain stands by its commitments on the border and stands ready to work with the European Union and Ireland to deliver a solution.