Do men always think about their exes even if they are in much better relationship now?

I am dating a guy who I knew long before we started dating. I felt the sparkle in between us but we were both in relationship back then. Later, he confessed that he liked me a lot when we were talking. He was dating a girl, let's call her L. They were together for 3 years, and she broke up with him on their anniversary. 2 month later, we started dating and it was a match we've never felt before. According to his words, after the start of our relationship, he understood how fucked up some things were with his ex. He said he of course accepted all that before because she loved her but now he realized how bad it was. He said he never had a feeling of not wanting to leave her place, he was used that they can't do things together and they rarely did - they had different interests but still managed to stay together for long. He was her first boyfriend (they started dating when she was 20) but then she dumped him one morning. He was very hurt, partly because he did not expect that it would go the way it did - she went on a vacation with her family, they didn't see each other for a month but then he came to her country to visit her and it felt like she never missed him. She was very cold all the time, and after he left she called him to break up with him. When we started dating, things were so amazing. He told me he could finally be who he was without "fixing" his character and without controlling his behavior how it was with his ex. I loved him for he was and I think he is an amazing guy. We are V together for almost a year already, we had a coupie of arguments but nothing huge, we were finding a way out of everything together.

It may sound like great relationship but after having read a dozen of threads about guys forever loving their first long term relationships, I get anxious. I have been wondering if he got over her, if he still thinks about her because she broke his heart. Of course, a breakup is never easy for anyone but r it always the case with guys that they keep this attachment to old relationships and still think about their "first love"?