by romance, i think people mean – make it romantic – showing the girl that you care about her, etc. – which means buying her chocolate, flowers, etc.
for people who only date a few times before getting engaged – this should be done in marriage and maybe, while engaged.
for others, should be done, while dating (once it’s going somewhere), engaged, and while married.
Being romantic when married is a very Jewish concept.
question only is when dating and/or engaged – and that depends on who people are and where they are coming from – when in doubt, ask a rav. may be extremely surprised at his answer.