First of all, I'll condition this with the fact I am a trainer. What the OP is experiencing is not uncommon or even bad. It happens and especially around the amount of time they have been married. My doctor even mentioned it to me a few years ago when asking the yearly check up questions and asking about sex life, performance etc given I am in my 40's and that is when ED starts to show up apparently. Apparently some of the "ED" experienced by some males can be traced back to attraction. And it doesn't matter if you married a Victoria Secret model or whatever. Being with the same person for a long period of time can lead to a lot of things that can make both men and women feel less attracted to each other and part of it is the exaggeration of the other's body imperfections. That was his explanation and I found that extremely interesting. So for those jumping on the OP, remember, marriage is hard and staying attracted to your spouse takes works always.
With that being said, as TXTransplant stated, genetics can play a big part in how a person ages. While I may not agree that weight gain after a baby is an absolute unchanging event, there are hormonal issues and the condition she mentioned, diastasis recti. But there are ways to fix it in the gym. Isometric hold abdominal work is actually great and many of the female trainers I know who specialize in post pregnancy use that with great success. It would be wrong to think that she is at the point of no return at her age, but it may require a lot more work in the gym and especially at the dinner table and not everyone wants to put up with that level of BS. I know women who have had diastasis recti and gone on to compete and win fitness shows. But it's an extreme example and takes a lot of sacrifice and discipline. Things that are hard for all of us. But usually if abdominal fat is an issue, the diet is the first place to look and get cleaned up. All the sit ups, crunches, planks and hollow body holds in the world won't lose belly fat. Only nutrition does that. All that said, it sounds like OP's wife doesn't suffer from post pregnancy issues, at least aesthetically.
OP, the final issue is this. She does need to want to do it and be the one who decides to do it. But she needs to strength train and eat well not for aesthetics alone. Instead, she needs to do it b/c she is a woman and very susceptible to osteoporosis at a later age if she doesn't start training with weights and exercising soon. Studies prove without much doubt at all that weight training/resistance training dramatically lowers a woman's chance of getting osteoporosis and as a son who is having to watch his mother be eaten up by it, I can tell you it's horrible and NOT something your wife wants. Also, if there is any family history of Alzheimer's or dementia, studies also show incredible positive results from intense strength training. Any auto-immune disorders she may have as well can be lessened or put into remission through intense strength training. Finally, until there is a vaccine for Covid, the BEST way to either not get it or be able to strengthen the immune system is to strength train, eat a very healthy diet and get plenty of sleep.
So there are some REAL reasons she needs to get back into shape, especially now that she is still young and can make it a steadfast habit and lifestyle the rest of her life.
With that being said, as TXTransplant stated, genetics can play a big part in how a person ages. While I may not agree that weight gain after a baby is an absolute unchanging event, there are hormonal issues and the condition she mentioned, diastasis recti. But there are ways to fix it in the gym. Isometric hold abdominal work is actually great and many of the female trainers I know who specialize in post pregnancy use that with great success. It would be wrong to think that she is at the point of no return at her age, but it may require a lot more work in the gym and especially at the dinner table and not everyone wants to put up with that level of BS. I know women who have had diastasis recti and gone on to compete and win fitness shows. But it's an extreme example and takes a lot of sacrifice and discipline. Things that are hard for all of us. But usually if abdominal fat is an issue, the diet is the first place to look and get cleaned up. All the sit ups, crunches, planks and hollow body holds in the world won't lose belly fat. Only nutrition does that. All that said, it sounds like OP's wife doesn't suffer from post pregnancy issues, at least aesthetically.
OP, the final issue is this. She does need to want to do it and be the one who decides to do it. But she needs to strength train and eat well not for aesthetics alone. Instead, she needs to do it b/c she is a woman and very susceptible to osteoporosis at a later age if she doesn't start training with weights and exercising soon. Studies prove without much doubt at all that weight training/resistance training dramatically lowers a woman's chance of getting osteoporosis and as a son who is having to watch his mother be eaten up by it, I can tell you it's horrible and NOT something your wife wants. Also, if there is any family history of Alzheimer's or dementia, studies also show incredible positive results from intense strength training. Any auto-immune disorders she may have as well can be lessened or put into remission through intense strength training. Finally, until there is a vaccine for Covid, the BEST way to either not get it or be able to strengthen the immune system is to strength train, eat a very healthy diet and get plenty of sleep.
So there are some REAL reasons she needs to get back into shape, especially now that she is still young and can make it a steadfast habit and lifestyle the rest of her life.