Whenever I try to write really meaningful, emotional scenes, I want them to be a little slower, more descriptive and everything, but they always come out too short and quick?

Here’s a few things you might try doing. 

1. Use the setting to build up (or, alternatively, contrast) the mood. 

Imagine a funeral taking place on a cold, rainy day. Or a couple breaking up in a park on a bright sunny day. Having your characters take note of their surroundings - realizing how fitting it is, or feeling strange that their life is falling apart and everything around them is so normal - can help build up the emotional atmosphere in the scene. Pay attention to what your characters are sensing.

2. Pay attention to what your characters are saying. Or not saying. If they’re emotional, then they probably have a lot on their minds. Have them speak it. Or start to say what they want to say, but cut themselves short. 

3. Show, don’t tell. And really push the showing. Use your characters’ thoughts, observations, feelings, sensations, etc., to let the reader experience their emotions through them. Be sure you’re not just telling us they’re sad, or angry, or etc.