Read it. It is a wild ride, and actually has story to tell with symbolism scattered all over the place unlike so many other manga. Was starting to give up on reading manga until I read this, hope there are more as good as this.
Might be an age gap but he has objectively the same % of life experiences as she does, now.
Also why should she wait? He didn't expect her to, he just wanted her to live.
Why timeleap works always end in some depressing shit? Even that one with the kid going after his HS teacher had drama in the last chapters and "broke up" for some years before the happy ending.