Is it normal wanting my friends to be together?

Here's the story: two of my friends have an ongoing friends with benefits situation which they seem in denial about.

They are both female and one of them (friend A) is clearly in love, while the other (friend B) keeps getting into relationships with guys, which never work out.
Either the guy finds out about their special friendship (my two friends can't stay away from each other and usually end up shagging). Or friend B falls out of love with the guy, sabotaging the relationship then getting into a depression (which leads to A consoling her, if you know what I mean).

Those two ladies are meant for each other, they have so much in common, all of their friends know about what they do even if they think it's a secret, however, friend B keeps playing straight and friend A does not confront the other afraid to lose her for good.

I try to help friend A, encouraging her to open up to friend B, but they keep this crazy friends façade, it's been going on for over a decade.

Even if it does not work out they can't stop seeing each other because they are involved in the same project (one more thing in common) and it's very successful.

Should I sit with them and make them talk about it or stay out of their business? It bothers me since they are clearly in pain, specially friend B, who does not even hook up with anyone else, so involved that she is emotionally (without verbalising it, but she told me she loves friend A once when drunk).

Thanks for reading, sorry if it's confusing.