Be honest. There are probably a couple of things you haven't told your significant other. Whether it's something as little as the fact he/she actually has put on a bit of weight over the festive season, or something from your past like *that* time at uni -- most people have something stored away in their "I'd rather not share" bank.
But when does keeping a secret from your partner go from harmless to hurtful?
"I think a lot of people carry a lot of guilt if they have a secret. They think, 'ooh, am I doing the right thing?' My first response to this, is -- to lie or not to lie is a very personal decision," social scientist and relationship and dating expert, Melanie Schilling, told The Huffington Post Australia.
"It really comes back to your personal ethics and values. I can’t really say to someone whether it’s right or wrong to lie because that’s a moral decision they have to make.
"But I would recommend asking yourself -- 'what’s my motivation to lie here?' If it's for selfish reasons, then you might want to rethink it."
Matt Garrett of Relationships Australia says wanting to keep things secret from your significant other -- depending on what the secret is -- could be a sign of trouble in the first place.
"If you are keeping secrets from your partner, that's a yellow flag," Garrett told HuffPost Australia.
"That's not to say you have to reveal everything to your partner about yourself, but if it's something that implicates your partner in some way, withholding that information should be thought about carefully."
"I think there are a couple of questions to think about," continues Schilling. "The first one is, 'why am I keeping this a secret?' And the second is, 'is this about my own ego or is it about protecting the integrity of the relationship?'
"If you are keeping a secret to protect the relationship, and if that’s the motivation -- get a second opinion. Chat to a friend and say, 'OK, I have this secret and I am keeping it from him or her because I don't want to hurt them,' or whatever the purpose is.
"Because you might need a reality check. If you spend too much time in your own head you can lose sight of the bigger picture.
"One example is cheating. Depending on who you talk to, that can go from online flirtation all the way through to actually jumping into bed with someone.
"From my experience, that is the biggest one people talk and stress about, and worry 'do I tell or do I not tell?'
"My advice is -- if you are wanting to tell the person because carrying around that burden is so heavy for you and you want to offload it onto them, that’s a selfish reason and it's about your own ego.
"If you truly think in order for that relationship to continue being a relationship based on integrity, that’s the right reason to tell."
If the relationship is new and you are considering when the 'right' time is to divulge something, Garrett says if you're thinking about it, you should do it sooner rather than later.
"I see this a lot," Garrett told HuffPost Australia. "People saying, 'I won’t tell them now because we've only being going out a month or two and I don’t want to scare them off.'
"My opinion on that matter is you're only delaying the inevitable. That's my rule of thumb. If you are thinking about it -- just damn well get it over and done with.
"After all, you want them to know, you’re just worried about the effect it will have on your relationship.
"But really, if you reveal something about your past and it freaks them out and they leave you -- maybe it wasn’t going that well anyway."
For those thinking, "it's just a little white lie," Schilling points out the definition of what a harmless white lie actually is can differ.
"It can be fun to play the difference between a little white lie and a big old black heavy soul destroying lie and what the difference is," Schilling said. "Everyone has their own definitions of these things.
"I would say it's always good to get a reality check with someone you trust.
"If you actually slept with someone else while you are in a relationship, but in your mind you're saying it’s a little white lie -- that's an example of you minimising something that's quite serious in your own mind.
"Get a reality check and chat to your girlfriend or a mate. Get someone to hold a mirror up to you, in a sense. Have someone say -- 'you’ve actually slept with someone else. That is not a little white lie. That’s a big serious situation'."
Finally, it's important to consider the likelihood of your partner finding out about whatever it is you're hiding from someone else.
"All those decisions comes down to the individual and what you want," Garrett said. "But if there's a chance of them finding out independently, you may want to let them know before someone else does."