Lets compare Ian's relationship to the rest of (now dead) cancer crew:
Joji - kept his dating life private all this time.
Maxmoefoe - Has been dating a cute flight attendant for a while now.
HowToBasic - his identity never even got revealed iirc
Anything4views - He established himself as dumb and messed up from the get-go......which brings me to my next point...
If Anything4views was the one who decided to date someone like Anisa, nobody would give a shit, as he is messy and it would be expected.
Ian, on the other hand, built his career on criticizing certain popular youtubers that all commonly share flaws such as:
1) Being insecure
2) Ingenuine
3) Thirsty for attention
4) Dumb
Guess which one of these apply to his current gf? Yes, all of them.
Now I wouldn't blame him if Anisa seemed a nice, decent girl at first and then throughout the course of the relationship gradually showed her "true face", but that simply isn't the case.
Anisa was known as "Raihnbowkidz" , a twitch boob streamer. Before she got with iDubbbz, she was known to be dumb, she was caught lying, would start drama and of course, thirsty for attention:
And Ian, at the height of his youtube fame, decided to get in a long term relationship with her. He could have simply had a one night stand, he could've dated anyone else but a twitch thot, but the simp in him was just too strong.
TL;DR : iDubbbz has always been a simp.