couldn't part one temari just dash backwards while swinging her fan? i mean, she knows what neji is capable of.
True and likewise neji knows wat she's capapable of. The distance makes it very ncomfortable for temari here since neji is critically more agile and fast on his feet than her , he can dash to the side into the trees before temari gets her swing off and with his byakugan he can perfectly blend into the environment while constantly keeping close pace with temari who won't kno his exact location due to the speed that he's traveling along with the trees which also adds cover against her normal attacks.
The moment she backpeddals neji would already be on the move , usin his speed along with the already close distance to take advantage of the element of surprise to blitz her w/air palm and/or use his agility w/speed to manoeuvre around temari usin the environment , to get in CQC and unlike tayuya neji's not trying to use distance on her and will have full situational awareness on everything temari attempts along with his info on her jitsu meaning he guns straight for her giving her no time to feel ccomfortable to use any large scale jutsu.
At this distance the pressure would be on temari to gain distance while neji would simply need to use his radically superior movement speed abd agility to keep it intimate.