Oh I had a very similar situation about a year ago and it still kills me. Sorry for the long post it's quite nuanced but it's just so odd!
I met a mum at school who'd just moved here from Romania to live with her British DH and her own DD.. Get on like a house on fire (her English is perfect) and our DC were besties. Friends is about 7 months pregnant at this point. I also got on 'ok' with her DH but he gave me the absolute creeps and as a survivor of DV myself, I am as certain as I can be without witnessing something, that he's controlling & segregating her.
He works from home and she doesn't drive so any time we met up, bar once, he was with us.
Friend has her baby, so I naturally don't see her for a few weeks but I do get to meet baby once which was lovely.
Her DH does school drop offs so I'd have small talk with him in playground most mornings. He was always polite to me, no issues ....yet.....
This niggling feeling that something wasn't right just wouldn't go so eventually I pluck up the courage to ask her straight. I made all the prefaces like "I really hope I don't offend you in any way with this, I'm only asking out of concern" etc and asked if he was in any way controlling or abusive? She said no and reassured me that she wasn't offended and said she knows I'm only asking as I'm a good friend to her. So I dropped it out of respect for her.
A few months pass by, everything's normal. Chatting on WhatsApp, sharing each week's homework with whoever's DD forgot it, etc. However I still have only seen her once since baby arrived? Though I just assume it's due to having a new baby! I remember it well. Although we are now 3 months down the line and by her own admission, she hasn't left the house with the baby once? Not my business though so I just continue chatting to her, being as supportive as I can and everything seems the exact same as it ever was. She contacts me just as much as I do her. All normal. Until...
Suddenly, one Monday morning, her DH walks straight past me at drop off and looks at me as I say "Morning!" {like I do every day} and he blanks me.... I let it go, but then it happens every morning for a week so I ask her if he's ok "Yes, why?" I explain and she says "Oh he says he hasn't seen you?" So then I gently add that well, actually it's happened every morning this week but I didn't think much of it the first couple of times as we all have bad days, right?! But it doesn't matter, no big deal! and she said "Please don't turn this into something it's not" 🤨
So I figured they must just be struggling with a new baby or have something personal going on? Whatever it is, is not my business. She knew I was there for her. So I assumed that was the end of it.
Nope. The blanking continued and from that moment on, I've had nothing but hostility from any attempt I've made to try and contact her, let alone find out what their issue is with me. I've been deleted from her Facebook & I've only had 2/3 cursory conversations with her via text regarding the children eg: "Just a heads up, (my DD's name) has chicken pox" followed by one civil response from her. That sort of thing.
I'm gutted! She was a fab friend...