Hello Sfast & welcome.
I may come back to this, but I'll give my first impressions first.
I think that it is great that she can still go out with girlfriends, even when married with a child. For some women, this just isn't an option.
Consequently, I think that it is great that you can share child-care, to enable her to do this. Congratulations on that.
Obviously, on the nights you are at home with your little boy, you can get lonely and agitated, after he goes to bed, but think positively ~ you get an opportunity to share some great father/son quality time, before he goes to sleep.
Also, do you, or could you, have a regular night out with your friends?
As for listening to the 'phone; ~ when out with friends, dancing to music, etc, it's very easy to lose track of time and / or not hear your phone. This happens with my kids and I worry myself sick when they are out, only to find that they had no reception or couldn't hear it ring, or didn't realise the time. That's probably all it is with her ~ she relaxes, knows she's OK and forgets.
Personally, I don't think that it is very good if you cannot contact her. You might need her urgently. What if the child ~ or you ~ were taken ill and you couldn't get hold of her!
You say that she sometimes gets back to you within 10 minutes, but that, at other times, you hear nothing from her ~ even after you are expecting her home. This is an unnecessary worry for you.
You say that 'she knows it drives me nuts'. Is there something else going on here? You are at home looking after the child, while she is out having fun, and she acts in a manner that deliberately 'drives [you] nuts'?!
Why would she do this?
Have you done, or do you do, the same to her?
Does she feel that you check up on her too much?
Why do you feel the need to keep ringing her?
Do you know where she is, who she is with, and when she will be home?
You indicate 1.30ish. That sounds about right if out dancing with friends.
You say that you 'phone her 'after a few hours' ~ how many hours is she out? ~ I would expect perhaps 7.30ish to 1.30ish??
Why, exactly, are you phoning?
Are you worried about her safety?
Are you worried that men will be chatting her up?
Are you worried that she may be chatting men up?
Are you worried about something concerning her friends?
Are you worried because you feel that she doesn't want to be with you & this may threaten your marriage?
Are you bored and lonely & just want her to know that?
Are you just anxious & want reassurance that she is Ok?
Back to your actual comments:
I didn't get married to sit at home by my self.
In some marriages, husbands & wives never go out together, in others they do, a lot.
Sometimes partners grant each other a lot of freedom, but trust each other, and spend other quality time together.
Some partners resent the time their spouses spend with friends ~ for no real reason.
In yours, what is happening?
Just your wife going out & never you?
If so, arrange for your own evening out.
But communicate! Say how you feel and why.
Don't sit there getting resentful.
Why not take up a hobby for those nights in alone, or with your son?
I'm not a fan of my wife heading to the bar with her girlfriends.
I know that you won't be alone in this, but ask yourself 'why?'
Ask yourself : 'Is your reason rational?'
Are you just being unnecessarily resentful, because you feel bored?
Or is it something more? Something more serious?
After all, she never did that sort of thing in the 3 years before we got married.
She didn't go out with friends?
Was this because you were courting & she was always with you?
What about before you met?
Everyone needs the freedom to relax and enjoy themselves with friends from time to time.
Did you go out with friends back then?
Now when she goes to the bar I am stuck at home with our son.
I wonder, how often is your wife 'stuck' with you son?
And I'm guessing that your son would feel heartbroken to know that during the 1-1 time you spend with him, you feel 'stuck'.
I don't mind being at home with him but she doesn't show much respect or appreciation that I am willing to stay at home for hours while she goes out to have fun.
Do you never go out & have fun?
Do you respect & appreciate the time that she spends caring for your little boy?
Who looks after him most?
Do you both go out to work?
I would rather spend time with her. But I miss out on two nice nights in a row with her because she is asleep by 8pm on the next night.
If you love her & want to be with her, do you tell her this?
Does she know that you want to spend time with her?
Do you tell her that you enjoy your nights in together?
Do you show your appreciation?
Would it be quality time?
If she were in, would you all be doing quality things together, as a family, or would housework and childcare get in the way?
Would it be special? Or just the mundane usual night in?
This main problem is that she doesn't answer her phone when she is out. ....
Yes, you have a child & you need to keep in touch, but this needs to be organised in a reasonable mature manner.
You should be told, in advance, where she will be, who she will be with, how & when she will be home.
You should be able to contact her in an emergency.
She should phone home once or twice to check that there are no problems ~ and she should phone to let you know if she will be home later than the agreed time, or if she is going to be at a different place or with different people from those originally stated.
Then there should be no need for you to keep phoning her.
So the question is: Is it unreasonable for me to expect her to keep in touch as I sit at home alone with our son until past 1pm?
Not unreasonable for her to keep in touch.
Not unusual for you to feel a bit fed up and lonely.
But if things are organised fairly, there should be no need for you to feel anxious or for you to keep phoning her.
Organise things fairly, so that you both get a chance to go out with friends.
But make sure you arrange quality evenings for yourselves.
Put fun and romance back into your lives.
How long have you been married?
How old were you when you got together?
See a counsellor if you really need help.
My original thoughts on this have mostly been incorporated into the above, but here they are again.
I don't know your circumstances, so it's up to you to sort this out between you:
At least once per month, each have a night out with friends and a night out together ~ just the two of you (get a reliable babysitter). Perhaps alternate weeks.
Both of you, when you are out separately, phone home once ~ maybe twice ~ during the evening, to check that all is well.
Arrange a time when you will be home and phone if you will be late. Make sure the other knows where you will be, who you will be with, how you are getting home & what time you will be back. This is fair & respectful & egalitarian.
Respect each other's right to have time together & time apart ~ and time with your little boy!