Not sure how much help I can be in the punny department, OP, but I agree with you that #tothegrave is too morbid.
Just a heads up that sometimes the best punny hashtags come from inside jokes or special interests the bride and groom have - and only you will know those...
And the best and most used hashtags are also the ones that are simple and easy to remember - the longer and more obscure the hashtag, the greater the chance that it won't get used or it will get accidentally botched/misspelled.
Re: Need help being punny!
Just a heads up that sometimes the best punny hashtags come from inside jokes or special interests the bride and groom have - and only you will know those...
And the best and most used hashtags are also the ones that are simple and easy to remember - the longer and more obscure the hashtag, the greater the chance that it won't get used or it will get accidentally botched/misspelled.
Here are some ideas:
#PartyWithThePetgraves
#PicturePerfectPetgraves
#PerfectlyPetgrave
#FromProposalToPetgrave
#PetgravePartyOf2