Unhappy relationship with my daughter

I find this post a bit confusing. You don't say anything about SIL, do you get on with him? how much of this could be coming from him but your daughter does not want to admit it to you? She may be acting to keep the peace if her partner for some or no reason is against you or perhaps doesn't know you very well and is shy, or afraid of criticism.

Do you invite them over to you as a family? What happens at Christmas?

I would be happty to settle for a few hours after school once a week, and as he gets older, your grandson will go to bed later when you babysit, and you will get more time with him.

I agree that you should leave once they are ready to eat, and it would be better to make it seem like you are wanting/needing to go, rather than being forced out.

I'm sorry, it could be so much better, but also much worse. They are a family unit now, and you and your husband are extras standing in the wings. This is the way it is for most of us, alas.

I assuming that you have tried asking her (when you are both alone together) if she feels there is a problem?

I agree with Assunta. You can see your grandson and babysit him which means spending quality time. You want more family time with your daughter than she wants with you. That does not make her wrong. I cannot see any option but to back off and understand that they like to have family meals alone with their small young family. I think that you need to accept the situation, being willing to babysit when asked, and enjoy your grandson's company.
Your daughter and SIL may be feeling pressured or under stress and, without intending to, you may be adding to that. Not everyone finds families easy.

I think you have to accept what you've got. Once a week is enough to have a bond with your grandson. When he's older he might start asking his parents if he can stay for a sleepover at your house. As for expecting meals. No! We never expect a meal when visiting our son or daughter. They work full time, have children to look after. They don't need to be catering for us. As Lucklegs9 says "make light of it". In fact make light of everything. Be cheerful parents and grandparents. Don't be full of resentment, because your daughter is picking up it.

Tread carefully, things may improve but if you say anything it may disintergrate drastically. I have 3 grandchildren that I (we) don't see, I have no idea why at all.

As the boy gets older he may want more time with you and once a week is so much more than many people here get, make the most of what you have, It is frustrating to be treated shabbily but I think it just isn't worth the gamble of tackling this.

Assents, understand you feel hurt but I am afraid there is little that can be done. You say you have a loving relationship with grandson, perhaps you could suggest taking him out for the day or could he come round for tea, if not at least you see him once a week. I would leave when she starts preparing evening meal, making light of it, no need for fish and chips either, not much of a problem leaving your meal ready to be reheated in the microwave. At least you have contact and things can always be built on. It's very easy to put your foot in it with some daughters despite that close bond they grew up with. I have no contact now with mine, it doesn't bother her seemingly but it breaks my heart. So enjoy what you have.

Assunta We have always been supportive and willing to help especially with our grandson but she has always preferred to cope without our help. Although very quick to ask us to babysit when it suits her!
In this paragraph you seem to be simultaneously complaining that your daughter likes to be independent, and at the same time complaining that she asks you to babysit..... perhaps she's as confused as I am.
You sound as though you're jealous of your DD's friends. Don't be. It's not worth it.
Do you ever invite your DD and DGS to your house?

I haven't any advice, I'm afraid. There are lots of grandparents who would do almost anything to get to see grandchildren who have been prevented from seeing them due to estrangement. I suppose, in view of that, it may be better to stay quiet
I just can't understand people like your daughter though.