Hes 18 months and its been going on a while.
Obsessed with Daddy. Daddy finds it pretty horrendous as he cant even go to the loo without hysterics, nor can he sit in a chair without DS barrelling over and flinging himself at his crotch. He is pestered. Sometimes he feels so claustrophobic.
Its not even a case of DH being the "novelty" parent as we both work only part time hours and are vboth always at home and co parent 50/50.
So he just prefers DH. 
DS likes me fine - Im calm and cuddly and easy to be around so whats not to like? But I dont know how much he needs or loves me.
Doesnt help that despite being pretty verbal he has never learnt Mummy and he doesnt kiss. Hes a fun child but really only cuddles me when I bring him for his nap. I store those moments in my heart like a saddo cos thats all Im getting.
DH feels sorry for me. Sometimes when Ive been upstairs and I come downstairs he says "He was going mad looking for you". But bless him, either hes just saying it to bolster me or hes seeing what he wants to see as DS has no gesture or word for me, so how could you tell he wasnt just moaning in general as toddlers do? And certainly DS doesnt seem to look for me when Im on the same floor, so...yeah.
He says "you're a great mum". But I know Im a good Mum. Im made that way. Its my pleasure and my duty. I still dont think my child would notice if I ceased to exist tbh.
And DH is a GREAT Dad. There is nothing hes too proud or lazy to do. Hes like a second Mum. So I suspect DS just doesnt need me.
Ironically DH finds the clinginess really really stressful. He would do anything to redress the balance. He feels he cant breathe with all the attention, hes touched out.
Anyway, theres nothing to be done, is there? We just have to grit our teeth and get through it.
Just needed a moan tonight as this evening DS may as well have been wearing a bloody sign saying "Mummy Who??" and DH has developed a stress migraine.