Maybe the issue isn’t whether he loves you or not, but rather that he doesn’t truly understand you. Does he really know what kind of person you are, what you value, and the importance you place on your family? If he doesn’t, he may have filled the void in his mind with his own prejudices 
Maybe the issue is neither his understanding of you nor your understanding of him. In marriage, everyone has expectations, but when family comes into play, the balance can easily be upset. In this case, could it be that your mother-in-law’s concern is not you, but the life her son has built with you? She might think that you’ve placed him in a position that feels less important than her.
The reason he’s having a bad relationship with you might not be about you, it could be related to how he approaches your spouse’s family. For example, he might be blaming you because he no longer receives the same attention he used to. How does your spouse treat his mother, what has changed, take a look.
Maybe you need to stop trying to measure your mother-in-law’s love and start questioning the meaning you give to her. Why is it so important for you to get her approval? What would happen if you tried to create some distance?
Whether they love you or not, one thing remains unchanged: Your communication with your spouse. No matter what your mother-in-law does, the main point affected is there. If you don’t turn to your spouse and ask “how is this situation affecting us,” you’re just preoccupied with side issues.
Maybe you need to ask your mother-in-law directly before your spouse. Ask her why she is showing this distant attitude, if she has any issues. If things get worse, at least you won’t be left wondering in your mind with an “I wonder”.
Maybe the issue isn’t that he doesn’t love you, but that he can’t share his son with anyone. These kinds of people don’t confront directly, but they draw boundaries with little actions. Do you think the bond he has with his mother’s relationship with you might have been affected?
Perhaps the issue is entirely related to her past experiences. Could it be that she unconsciously carries over a struggle she faced during her own bridal period into her relationships with you? How was it with her own mother-in-law, have you ever talked about it?
Maybe they don’t really like you at all, but do they have to like you? I mean, we don’t have to have a “warm” relationship with everyone; there’s no rule that says we have to like each other. I think as long as you keep fixating on whether they love you or not, they feel more at ease. What would happen if you focused less on this “love” issue and left some space for what they might do instead?
Now, there might be something like this: Could it be that your mother-in-law doesn’t dislike you, but is rather intimidated by you? Some people feel more comfortable keeping their distance, thinking they might lose control when they get too close. It might be entirely a defense mechanism. Have you ever thought about it from this perspective?
So how does your spouse behave in these situations? Are you always the one looking for a solution to the tension you experience with your mother-in-law, or does your spouse somehow get involved as well? Because their stance can be very determining in the balance between you two.
Even if he has issues with you, is it normal for him to try to solve them by bothering you? If he doesn’t accept the reality that you and your spouse have built a shared life, isn’t that partly his problem? Why do we have to tolerate every move just because he’s your mother-in-law?
I think you’re reading too much into the situation. Maybe all they’re doing is living their own life without paying too much attention to you. Is it necessary to look for a deep reason behind every distant attitude?
Something caught my attention, how significant is your role in their relationship with your spouse’s mother? I mean, has your presence changed their dynamics at all? Perhaps the main issue isn’t between you two, but rather in the breaking of that old arrangement.
Could it be that what you always thought was “they don’t love me” is actually that they are constantly trying to control you? Because sometimes, such distant behaviors are merely an effort to observe you and measure your boundaries. Instead of obsessing over whether they truly love you or not, it seems like you could understand better by considering how much they want to control you.
Maybe the issue is neither love nor control. Your mother-in-law might just be defending her own territory. She doesn’t see you as a direct threat, but could she think that as a new person, you’re disturbing the balance? That’s why her attitude is more mechanical and distant.
I think it goes back to the simplest question: Did they say something clear to you? Did they show an open attitude about not liking you, or feeling uncomfortable? Or is it always your interpretations? Because sometimes what we feel isn’t the other person’s direct stance, but our own sensitivity.
Did she make it clear that she didn’t care? you said, but not everyone puts everything into words. With a passive-aggressive tone and small gestures, one can convey a clear message as well. I think we shouldn’t get caught up in whether she said it or not; don’t overlook the behaviors.
But has he ever shown passive-aggressive behaviors towards you, for instance? I mean, does he do things that bother you secretly and then act like a completely different person towards his spouse? Because this duality is important. If your spouse also notices the same things, the issue can be discussed more clearly. If not, then either it really doesn’t exist, or he is deliberately staying silent.
Is your spouse taking sides on these things, being neutral, or completely out of it? Because their stance also influences your mother-in-law’s attitude. Maybe they’re not aligned with you, and this could be creating an obstacle you’re unaware of.