Romance should be a skill IMO. Start out with horrible pick-up lines and awkward interactions. Be labeled as 'the creep' and eventually building up becoming the 'master romancer'. Once our sim has mastered the romance skill then proposals could be more extravagant like lightning flies spelling out 'Marry Me'. If your sim proposed on level 1 skill they could propose while looking at another sim, or say the wrong name- awkward.
And a matchmaker career would be very fitting for a Finding Love/Romance pack. Set up speed dating events, build up a clientele of hopeless romantics and learn about each sim that comes to you in search of a soulmate. Our sims could play around with different chemistries and either find the 'Match made in Heaven', or 'Match from hell". Our matchmaker could also mentor in relationship advice, help sims with their romance skill, and write books on romance, dating and relationships.