@Goyal99Raj It's because they're part of different clans and are naturally like that towards each other. It's his first time interacting with someone from the wood clan so he can't really control this natural impulse. Look back when he had some metal ki in him and how he initially treated her - he's improved a lot since then.
Basically this. Noh Mah Mah briefly mentions the relationship between the various clans, but it's best to kind of think of it more as a balance and a systematic force, rather than a simple rock paper scissors "x beats y" kind of thing. Each of the elements constrains or builds up the others, and is itself constrained and built up, but they are not necessarily in conflict, even for the elements which are in opposition. When Noh had the metal ki in him, his instinct was to destroy the wood clan girl(when he was letting out all that bloodlust), and he was apprehensive about fighting the fire clan dude. Once the Metal Ki was drained out of him, his attitude towards the fire clan dude became more respectful, while his behavior towards the wood clan girl became more controlling. When ki is out of balance, superior elements will overwhelm or destroy subordinate elements. When ki is in balance, the proper relationship between the superior and subordinate elements is control or regulation.
Interestingly, the dominance relationship between the elements is referred to as the father-child relationship. The generative cycle(i.e., the reinforcing relationship between elements, like metal and water) is referred to as the mother-child relationship.