The MC is dumb so he has 2 points of intelligence, so he will never increase intelligence because he's dumb.

He doesn't have any stolen ability yet so there's no specialization to work with, and as an ability stealer it's pretty easy to see his main advantage is the diversity of his stolen abilities. To that end, it's better to start by evening out his stats. Yet his first action is to put several points into strength and that's it. Not one point to test the feeling and not more, not point in various stats, no. several points in strength, with no knowledge of if he'll need these points elsewhere later. That shows no intent of saving all his points, yet also no intent of applying any of those points elsewhere.

The childhood friend has been in love for 10 years, and he doesn't see her as a love interest. There's potential as a misunderstanding makes her send the biggest signals in her lifetime, and he doesn't just fumble, he literally doesn't compute his own culture and language. And then as if the author wasn't satisfied with making the relationship less appealing to the reader, he fantasizes about her begging to be 31st in his harem as he leaves her behind. Who did you say you couldn't see as a woman and that's the entire reason you didn't understand her signals? Who is supposed to be your childhood friend and the only person who treats you like a human? Who literally told you would subsidize you for life if you couldn't succeed in life? And the first time you even think about her it's this?