Move into nonhostile space attack and move

Question

Moving Around Other creatures

You can move through a nonhostile creature's space [but] you can't willingly end your move in its space.

Is that "end your move" at the end of your turn or if you stop to attack? I had a player who wanted to move into another friendly character's space, attack a hostile, then sidestep behind a wall.

Answer 1

You can't end your movement in an occupied space, as the rule you quoted says. When you move in 5e, you are free to spend your "feet of movement" how you like during your turn. This does not exempt you from the clause that states you cannot end movement in an occupied square. The full order of actions would be:

1. Begin with 30 feet of movement (assuming your speed is 30)
2. Move 15 ft to occupied square — can't stop here because it's occupied, move to closest unoccupied square
3. Attack if able
4. Use rest of movement to move behind wall

This is confirmed by Jeremy Crawford in a tweet:

Jeremy Crawford ‏@JeremyECrawford · May 3 2016

You can't willingly stop moving in another creature's space. #DnD

Answer 2

Movement is not a defined action like it was in 4e

Your move speed is effectively how many squares you can move on your turn and you can break it up between other actions you take (multiple attacks as part of the Attack action and/or free actions like dropping a held object) thus when you stop moving to do something you are "ending your move." Because the same section of rules you quote starts off saying you can move through non-hostile creature space.

Answer 3

Yes you can

I am aware of this tweet and I think its wrong.

The rules say:

Movement and Position

On your turn, you can move a distance up to your speed. You can use as much or as little of your speed as you like on your turn, following the rules here.

and:

Breaking Up Your Move

You can break up your movement on your turn, using some of your speed before and after your action. For example, if you have a speed of 30 feet, you can move 10 feet, take your action, and then move 20 feet.

Moving Between Attacks

If you take an action that includes more than one weapon attack, you can break up your movement even further by moving between those attacks. For example, a fighter who can make two attacks with the Extra Attack feature and who has a speed of 25 feet could move 10 feet, make an attack, move 15 feet, and then attack again.

and:

Moving Around Other Creatures

Whether a creature is a friend or an enemy, you can't willingly end your move in its space.

The rules permit you to insert your action into your movement anywhere and prohibit you from willingly finishing your movement in another creature's space. They are silent on using your action while within another creature's space so we should adopt this tweet:

Beware of claims that a rule does something mentioned nowhere in that rule or elsewhere in the core books. There aren't secret rules.

Presumably, we should beware of claims by the author of both tweets where Sage Advice continues to remain silent on the matter.