You've been dating for a while now, say six months to a year, and you want to take your relationship to the next level.
So, you've decided that it is the right time to move in together. I mean at this point you might as well, all your stuff is always at his/her place and it just doesn't make sense to pay rent for a place you live in part-time.
Eventually, you'll want to get engaged or married - so this seems like the "right thing to do". Isn't it?
Unless it's one of the following scenarios,
1. You bought a place together/share the rent.
2. You are engaged
3. You are from a different city/country and are staying at your s/o part-time.
You should WAIT and take your time before taking this very crucial step in your relationship. Couples who move in together before getting married tend to:
Get too comfortable.
Which is normal, and which you should get - but not comfortable to the point where you treat your other half as if she is one of your boys and lead the same lifestyle you did before you lived together. If you move into someone else's space, it's inevitable it'll always remain their space. Therefor if anything ever happens and you were to break up, you're the one that has to pack your bags and go - not him.
Fight about money.
It's a very touchy subject and if it could be avoided for the meantime, it should. If you move in with your s/o you need to treat them initially like a roommate. How are you splitting the groceries? The hydro, wifi, parking bills? Unless you've got a very organized budget where you both decide to pitch in for X amount equally (which rarely happens) you'll end up getting into fights with the one person you love most. It's easier with a roommate because there is no intimacy or attachment there.
Lose that "je ne sais quoi".
There's something nice about missing your s/o during the week. Not seeing them for just one or two days can make that time together that much more enjoyable. When you are living together, you never have your "alone" time which everyone needs.
Reconsider their entire relationship.
When you see the bad habits of your s/o (such as leaving the dishes in the sink, not flushing the toilet, or leaving hair in the sink) when you are living together, you will be surprised how much less you'll want to deal with it in the long run. It's much easier to walk away without any "real" commitment. You will want to comprise with your fiancé or husband because you've chosen to take that final step with them, but with your boyfriend or girlfriend, it's a different story.
I have seen MANY couples living together for months, and then breaking it off all together because the timing was off. I even know someone who was living with his girlfriend for 8 years and broke it off then met someone new and within 6 months got married. (They've now been happily married for 25 years). From past experience I find that living together especially in a place that you don't BOTH own, can make for a recipe for disaster.