Biggest problem topics I've encountered so far:
- Stuff that makes me cry for no reason (he hates that)
- Problems not ready for a solution; complaints without action
- Exes (especially, reasons to hate them).
- In-laws and whether we are acting like them
- Your unflattering opinion of his friends; religion; or hobbies.
- Divergent dreams; fantasies that don't include each other.
- Things we wish he did 'better' (encourage effort, don't demand change)
- Who you had to backstab to get him ;-}
- Where you bought the 1 thing you can actually 'cook'
- How much you paid for that (dress, food, gift...)
- Anything that starts, "You always..." or "You never..."
- What happens behind the closed bathroom door.
Secrets that are painful, but better to tell:
- Things you really don't like in bed / in romance.
- When something he does is hurting you.
- Medical info on a need-to-know basis for safety (allergies, chronic illness, STD, etc.)
- Whether you expect an 'open' or 'closed' relationship
- Direct knowledge of something that could cause him trouble (e.g. your ex is gunning for him at work, or your sister is a nympho/klepto who steals your guests.)
- Deal-breakers: if you have a secret that won't change, and may reasonably cause him to flip out or feel betrayed ... like,
- you are really a man,
- have already slept with his father
Tell him early, and get it over with.