Yeah, having read this novel, this is true. He is an old. ╮( ̄▽ ̄)╭
His magic is so strong, it won't let him get physically older until [spoiler-ly archmage stuff happens], which means that he can then grow old together with the FL.
And anyone who calls this a grooming novel has clearly never read one. It may be one with a super-huge age gap, but that's not the same thing.
No, you're the one who needs to read a dictionary. "Grooming" and "problematic age gaps" aren't even CLOSE to the same thing.
Grooming implies him raising her to do things that a normal child would not do, or involve her in a relationship that she does not want.
El hasn't done any of those things. She took one look at him and imprinted. Her behavior is not normal, but he had nothing to do with that - the only reason he followed her to school was because if he didn't, she was going to stay with her abusive family for that they could be together. He doesn't want her to get hurt - that's normal. (He's also aware that her love is completely innocent, and isn't trying to change that - he just wants her to comprehend the words that are coming out of her mouth.)
Would it be less problematic if she got together with someone else? Yes, definitely. At least the prince is her age, and he likes her. He's also the most reasonable option. It's just unfortunate that El is endgame.
"she imprinted on him" yo she isn't an animal, you said it yourself he know her feelings and he doesn't reject her, he doesn't distance himself, he spend all this time influencing her behavior and then got together with her when she was of age. Grooming doesn't always mean that they will do psychical stuff when she is still a child, but they will influence the emotions and behaviors of the victim, just because he looks like a child doesn't mean he isn't an old dude who fall in love with little child and then married her, there's no world when this isn't disgusting. Moreover works like that normalize big age gaps for young readers who might then become a victims themselves.
Thisss. This OLD MAN is influencing her decisions simply by being in her proximity and presenting as a male of similar age to her. Because he is with her, she will make decisions she wouldn't have otherwise. She will have romantic thoughts earlier than she otherwise would have and she will already be "set" on him before she is of an age where she can make a sound decision. He doesn't seem to do anything to dissuade her. Not to mention he will definitely have feelings for her early and these feelings will influence his thoughts, words and actions, whether that was his intention or not.

No but why the age gap is so big? It's literally disgusting grooming, she is freaking 14 years old