DD married 18 months ago and has dropped the bombshell to me today that she wants a divorce and asked my advice. Apparently she’s been feeling this way ever since the excitement of the wedding wore off but had tried to put it to the back of her mind. DD and SIL have been together for a long time, since they were both 18 (she’s 27 now). SIL is lovely and very much part of our family. We are close with his family also and always celebrate Christmas and birthdays together. Both families would be shocked and devastated if things were to end. DD says just doesn’t think she loves him anymore. The only real reason she could give is that she thinks she met him when too young/wouldn’t choose him now and is tired of carrying the mental load (he can be a typical man at times, a bit forgetful and messy around the house). I’m told that poor SIL knows how DD is feeling and is desperate to make things work 
I pointed out to DD that there are men far worse than her DH and that if there has been no infidelity or abuse, she should be prepared to work at the marriage as she has made a very serious commitment which shouldn’t be ended recklessly and turn their lives upside down. AIBU? They don’t have DC yet but have committed in many other ways, for example they own properties together.
DD is now upset with me for not being supportive, yet she asked my opinion. Should I have lied? Her view is that she doesn’t want to waste a minute longer in an unhappy marriage and wants to move on and find someone else before wasting her time further. All I ever want for DD is for her to be happy, but I don’t want to see her making a terrible mistake which can’t be undone... I’m all too aware that the grass isn’t always greener.