How can I help my brother move on from an unattainable love?

Im writing this on behalf of my little brother. he's 26 and has been in love with this one women for years unfortunately she's married, slightly older and just had her first baby so there isn't a chance in hell.

They both met at work and then later on found out our mom's were both good friends at there workplace too and known each other for years. She even had playdates with us when we were younger just obviously when you get older you don't remember these things.

They also found out they had loads in common and similar interests and became really good friends. My brother was in a relationship at the time of meeting her and he found she was too. Not long after though he broke up with his girlfriend for a number of reasons and one of them being he was falling for this women and she knew it.

she's 28 now and married to a slightly older guy with lots of money and he seems to make her really happy but she did admit to my brother but there was mutual feelings there and it wasn't just all in his head but out of respect to her partner she told him it best to distance themselves from each other and told him to focus on travelling and doing all the things he wants before settling for someone which he did.

He left his workplace and became a photographer and now is doing a lot of travelling. Meanwhile she got married which he pretended to be happy about for her.

Then he met Tina. Tina is lovely but she looks the spit of this women he's still in love with. They are constantly breaking up and getting back together. Then my brother found out this women has had a baby and he's beside himself. He won't amit it he just locks himself in his room now, doesn't answer his girlfriends texts and smokes weed.

This women is very pretty and got a great personality but i dont know why he's so hyper focused on her instead of looking for something else. He knows its not gonna happen so needs to move on instead of self pitying for the next 5 years like he already has been.
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I forgot to mention his girlfriend is a distant cusion of hers. He said he didn't know that but I don't know about that.
How can I help my brother move on from an unattainable love?
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