In Harry Potter There is quite a bit of romance and some people might of married someone else [and maybe for some if they haden’t died] some people broke up and some stayed together and got married.
Ron might have married Lavender. They were together in Harry Potter and the half blood prince and broke up in Harry Potter and the half blood prince.
Harry might have married Cho Chang together in Harry Potter and The Order of The phenix split up in Harry Potter and The Order of The phenix.
Hermione Granger and Victor Krum together in Harry Potter and The Goblet of fire never really split up.
Neville Longbottom and Ginny Weasley never really together but went to the yule Ball together.
Ginny Weasley and Dean Tohmas together in Harry Potter and The Half Blood Prince split up in Harry Potter and The Half Blood Prince.
Harry Potter and Hermione Granger Never together but seemed like the perfect pair.
Luna Lovegood and Neville Longbottom never together but probaly would have made a great pair.
Luna Lovegood and Harry Potter never together but might have made an OK pair they a lot in common.
anything might have been possible but i think in the end it was Harry and Ginny and Hermione and Ron the others i am not too sure about.