My son is in love with a woman 20 years his senior ?

They just got engaged.  :(
They've been dating for 3 years now. He just turned 21 and she is about to turn 41.It gets worse.They met when she was 33 and he was only 13. My son was 6 foot 3 and 14 stone at 13 and he was sexually active. He lied to her and told her he was 22 and they stared dating and were intimate before she found out. She did leave him after she found out he was 13 (I think they were togehter for a few weeks only) and he did pursue her for a few months after that very aggressively...I have to say she has done the right thing at the time and started dating a man more age appropriate and left my son be a child.However, he never gave up on the idea that they will be togehter and this obsession of his of reconnecting with her affected all his desicions. (He didn't go to u university and started working at 17, so he can earn his own money and get his own place.) He started pursuing her again the day of his 18th birthday and they have been together since he was 19, if not sooner.She does make him very happy (for now) they're even planning children...My question is, does this qualify as almost grooming of a sort?I'm not saying she groomed him, as she tried to do the right thing, but the situation might have been such that my son was groomed none-the-less. He was obsessed with this much older woman since he was 13.What should I do?Please state your age, I'd want to have some idea of the age of the people who are giving their input.

2019-11-28T18:52:18Z

He never had a proper relationship with anyone else after he met her at 13. He had some casual relationships and first long term one was again with her. I am simply worried. I know he is capable of making his own decisions on anything else. I'm not sure when it comes to this woman. 

2019-11-28T19:09:19Z

My son is a very talented coder with career prospects. Nothing too detrimental has occured.

I just feel like his childhood was abruptly interrupted at 13. He was never the same. Related to his peers poorly, chose to get a job and opted out of uni...

He never had normal adolescence. He spent it stalking his now gf telling her not to marry her bf at the time. 

I am not an overprotective mother. I am a normal mother with an outlier son, worried if his attachment to this woman might be unhealthy.

Anonymous2019-11-28T18:44:22Z

You should leave them alone. You’re not responsible for him anymore. 

If you don’t approve of the engagement, tell him that and why. 
Treat the kid like an adult with less life experience than you have, not as  
your helpless baby. 

It’s none of your business how old I am.

Where were you when he was 13? All you can do now is advise. Be glad you can still do that.