Adapted from a recent online discussion.
Question: My husband and I are lucky to live close to both of our mothers (one is widowed, one divorced). My mother-in-law is a very sweet but boundary-challenged lady who constantly invites herself along when she hears (usually from my husband) about our plans.
Making matters somewhat worse, I am very close with my mom and would like to be able to invite her freely without feeling obligated to invite my mother-in-law as well, but my mother-in-law has been hurt when she wasn't extended such invitations. Again, my husband is usually the one inadvertently alerting her to my plans.
Do we have an obligation to include her in a way that's exactly equal with my own mom? She's recently retired, so this may self-correct once she finds a routine of her own.
Answer: Exactly equal, no, but mindful of your mother-in-law's feelings, yes.
Make the effort to include your mother-in-law regularly on your terms.
That might seem counterproductive, since your apparent goal is to see her less, but including her deliberately - with manageable frequency - will help you say no to her at other times, which in turn will help you with the larger issue of boundaries.
If she's hurt about not being included when you do X with your own mother, you can hold your ground more comfortably when you're able to say, "Let's find a time when you, Husband and I can do X, sometime in the next few weeks" - or, even better, "I understand that you feel [whatever she's feeling]. I'm looking forward to Y next weekend, though," with Y being a plan you or your husband already arranged with her.
And when she invites herself, "I'm sorry, this isn't a good time to come along, but what are you doing next [date you're able to offer to her]?"
Obviously this goes a whole lot better if your husband is not only on board with this, but also taking the lead in making plans and setting limits with his mom. Otherwise his constantly feeding her these opportunities to get hurt, paired with not doing much to help, will start to shift your frustration from his mother to him.
Maybe her establishing a routine will take care of this problem entirely, but if the issue is that she feels excluded, inclusion on your terms will likely work better than just trying to hold the line.
Reader comment: Also, have a talk with your husband about telling her about your plans. He ought to realize it's causing problems, and he needs to do the, "Oh, sorry, that won't work but how about some other time?" thing even more than you do.
Answer: True, and I should have said something to that effect. However, I also suspect that if he hasn't stopped blabbing to her by now, then there's likely a reason he hasn't. Maybe he has no filter, or doesn't want to guard his every word to her, or Mama asks pointed questions, etc. Shutting off the information spigot always seems like an easy answer, but usually part of the relationship gets cut off with it.