Fucking hell, ignore what @pallasathena said because they seem to have been caught in some kind of weird sexist time warp!
You have done nothing wrong, op. You're not 'needy'. It is not wrong to expect that after a year and a half of being emotionally involved with a committed partner, that you would have some form of communication if things weren't right.
Your partner of 18 months has, for whatever reason, chosen to distance himself.
You have no way of knowing why, and as he's not telling you, you can only work on your own reactions.
Why do women constantly think that they should minimise themselves in case they 'upset' their man because they're being 'needy'?
If he's had a change of heart, he needs to communicate that to you. If he's struggling with something, he needs to communicate that to you.
You're not needy. You have a perfect right to have your partner of 18 months be straight with you.
Why do women set their bar so low?