Mourners for Liam Curry, 19, and Chloe Rutherford, 17, were asked to wear pink or blue for the service at St Hilda's Church in their home town of South Shields, South Tyneside.
The teenagers were among the 22 people killed in the terror attack on the Ariana Grande concert last month.
Miss Rutherford was studying music at college and was about to start an apprenticeship in travel while her boyfriend was studying for a degree in sport and exercise science at Northumbria University.
The Rev Fr Chris Fuller addressed the mourners who packed the church and several hundred outside, telling them: "Chloe and Liam were and still are an image of love.
"Inseparable in life, inseparable in death, inseparable now with the angels of heaven."
Two white coffins bedecked with flowers were carried in to the church together.
Flowers in the two hearses spelled out the words "Sis" and "Son Liam".
The funeral of Georgina Callander, 18, from Tarleton will take place today.