The original Lalitavistara sutra was taken out of India, i. e. the version where the period of His love life is included. It circulated widely, it had a vast influence, this influence can be seen in such literary works as Boccacio's Decamerone and Chaucer's Cantenbury Tales. They both have a stamp of Shakyamuni's life story, the feeling of the real existence of Bhagavan Shakyamuni.
According to Etienne Lamotte Gopa is mentioned as Shakyamuni's wife in several other Mahayana sutras besides Lalitavistara, in the Shurangamasamadhi sutra she has a chapter, and she features also in the Suvarnabhasha sutra. In the footnotes of the Shurangamasamadhi Lamotte says:
" According to the Mahayana Upadesha of Nagarjuna bodhisattva Siddhartha had two wives; first was called Gopa or Gopiya, second was called Yashodhara, first one did not give children."
"Mulasarvastivadin Vinaya attributes three wives to Him, each surrounded by 20 000 courtesans: Yashodhara, Gopa, and Mrigaja"
"Seven days before the Great Departure when the future Buddha was returning to His palace Mrigaja addressed Him with the famous stanza: Nibbuta nuna sa mala; Shakyamuni in thanks cast a necklace to the young woman,"
(T 1450, ch3. p. 114b, Rockhill op. cit. pp 23-24)
Buston's Blue Annals mentions that bodhisattva Gautama had two wives and gives their tibetan names.
In a Driking Kagyu life story of Siddhartha you find:"In addition He accepted other Queens and their retinues, totalling 84 000 in all."
( The Great Kagyu Masters the Golden Lineage Treasury, Snow Lion 1990)
Modern ethnic buddhists tend to be lutheran-protestant in style and attitude, they automatically make Siddhartha Gautama a monogamous person, therefore you must value this statement, that Drikung Kagyu has told us, as something very precious.