Hi! Thanks for the question!
Firstly I would request you to make 'A public place' a liitle more clear.
Except that, yes, you can be questioned or held for an act that is covered under the definition of 'Obscene' or 'Nuisance' in a public place which annoys the general public. This has been covered under Sections 292/293 or 294 of IPC (Obscene act or word) and also section 268 IPC (Nuisance) . However this will depend on the circumstances of the case and what kind of act is the couple involved in. Not any couple can be unduely mistreated for sitting and chatting.
Yes, these sections can be misused by the police in rare cases. However, a person is expected to behave decently in public and such a law is necessary.