Most girls will automatically assume that just because a guy is talking about his ex that he is still in love with her or still wants to be with her. But I don't believe that this is always the case.
After long relationships, we tend to look for the same qualities that our ex-boyfriend or girlfriend had in another person. So, once we start dating a new person it is very likely for us to bring our exes up in conversation and for comparison.
Just because he brings her up doesn't mean he doesn't care for you or that he doesn't want to be with you.
Actually it shows that he is comfortable enough to open up to you and express how he truly feels. What you need to do is just listen to him. Listen to what exactly he has to say about her.
Is he constantly reminiscing about the smell of her hair? Or those jeans she used to wear? Or is he saying things about her in a negative way, saying things like "My ex did ____ and I absolutely hated it" or "I can't stand the way my ex brushed her teeth..."
He isn't saying her name or talking about his old memories because he still loves her.
Usually, he talks about her because he's just still a little hurt from her, and he's looking for closure. And sometimes the best closure is to talk it out. So the best thing you can do is be there for him and understand where he is coming from.
We have all been caught talking about our exes to our new significant others.
Is it fair? No. Is it life? Yes. Unfortunately it is true that dating someone who does you wrong makes you defensive and ends up making the other people you date have to "prove" their loyalty to you.
So they will end up talking about all the things their exes did wrong, so you can understand why it didn't work out with them.
He might be telling you things about his past relstionship because he hopes you two won't make the same mistakes.
And I know, it's not fun to be held to another person's mistakes, but it happens in almost every relationship. And I can reassure you, it doesn't mean that he isn't into you or that he still wants to be with her.
If it is truly making you upset, tell him that you really want to be with him, but that you are NOT her, and that he needs to give you a fair chance if he wants this to work.
And explain to him that exes are in fact exes for a reason. And reassure him that you are nothing like her, and he picked you because you are different.
Remind him that you are the girl who is going to change his world.