My (31f) partners (28m) mother (62f) is overbearing and treats him like her husband.

To preface, my partner and his mother have gone through many traumatic things throughout his upbringing (abuse, moving to a new country, and then the death of father/husband) and they are from a country that is much more affectionate than North America.

my partner (28m) and I (31f) have been together for closer to 10 years and this issue has been consistent on my side but when I try to approach it, it obviously hits a nerve.

My partner and his mother had tumultuous teenage years but have gotten closer in the years since. Now, my partners mother is overbearing, to the point where she is texting him all day, requires him to call her at least once a day, and gets upset when he doesn’t. Their conversations are usually mundane about each other’s day, etc.

There is also the expectation of him to go over for dinner once a week. He usually goes alone as I feel uncomfortable there (she has made comments to him about my weight, and although she is kind to me I feel judgement eating there/relaxing), but on the off time I do go, she is literally cuddling him on the couch, hugging his arm and everything. They cuddle and watch movies together, and it feels like she’s projecting a husband-type role onto him.
His mother has a partner, and has for as long as we’ve been together, he is usually not invited to their dinners once a week (they do not live together) but when he has been there when I am (holidays, birthdays) there is NO cuddling behavior.

it doesn’t affect my daily life frequently, but it feels like she is basically trying to get her needs of her deceased husband from him (as he is their only child)

How do I approach this with my partner in the most compassionate way without creating tension?

TLDR – Partners’ mother treats him like a husband with consistent expectations of communication and spending time together. Uncertain how to approach the uneasiness of this without causing issues in a relationship.