Imaging you'd have a crush for that long and had even the first go, but you'd blow it for such a stupid reason as "He has to mature". I can see her shying out of the situation, because she was a coward (Alright, it happens), but coming back after 3 years and believing she can simply snatch him away? She was even fine with him having another girlfriend. (Maybe some sort of selfpunishment?)
I simply don't want to believe that inhuman crap about "raising him to a perfect husband for their common future happiness". I'd rather believe, she chicked out when she had the opportunity to strike and hurt him badly in the process (and talked herself into believing she did something good). But even then she continued to mess up. She messed up in days, weeks and months afterwards and is 2 years too late.
Now that I thought about it: Tadano's Chūnibyō phase was also powered by the need to make a good impression on her, in other words to appear like good husband/boyfriend material. Ouch...
If Tadano is a real Chad, his answer now should be clear.