'Gramma Mamma' here. :)
'Despite' is NOT a conjunction.
'Despite' is a preposition ( like 'for', 'on', 'with' and so on) so it must be followed by a noun, a noun phrase or a verb in the gerund form. It cannot be followed by a verb phrase.
'Although' is a conjunction, so you can say:
"Although John had recently broken up with his girlfriend, he was happy."
In the above sentence, the conjunction 'although' links the two parts of the sentence.
You cannot use 'despite' in this way. Grammatically, 'despite' is the same as any other preposition : you wouldn't say 'With John had broken up..' or 'Of John had broken up..', so you cannot say 'Despite John had broken up.' Here are some ways of using 'Despite' in your sentence:
"Despite the fact that he had recently broken up with his girlfriend, .."
"Despite having recently broken up with his girlfriend, ...' (gerund)
"Despite the recent break-up of his relationship,..' (noun)
So don't forget - 'although' and 'despite' are similar in meaning but different grammatically. One is a conjunction, followed by a verb phrase, and the other is a preposition followed by a noun phrase. Transforming sentences such as 'Although he was young,.' to 'Despite his age,... or 'Despite its high price,..' to 'Although it was expensive,..' is a basic exercise in all grammar books and English language exams. Remember that simple rule and you'll never go wrong.
I hope that helps.