Scarleteen

The same thing that could get me aroused to wanna masturbate in the first place makes me lose interest once I get a few seconds of instant gratification its like my brain becomes bored of it is this common

Another thing is arousal makes me have to go to pee every few minutes even though i didnt drink alot of water before is this normal

Hi again! Yeah, it's not uncommon for people to lose interest over the thing that arouse them every now and then. Some people may need more variety in their sexual lives than others, and that's fine.

As for your second question, arousal often comes with what we call vasocongestion a.k.a. increased blood flow to our genitals tissues. For folks with vulvas, the vasocongestion shows up in the erection of the labia and clitoris as well as the relaxation/loosening of the vaginal walls, the latter of which can feel like having to "pee." Have you read this article by any chance? Sexual Response & Orgasm: A Users Guide