This is similar to Who wins if two people have conflicting desires? and the answer there is just as relevant.

Would they then shift to a reality where a version of you also wants this type of relationship, meanwhile you are still experiencing them as only a friend in the reality you are in?

The Universe or "All-That-Is" is not constrained by what we (from our physical perspectives) perceive as the only choices available. If both people are in perfect harmony with their desires (and not pushing against the other's choice) then both must manifest a result that perfectly matches that vibrational harmony with their desire.

It's impossible to say what that outcome will be because it will be a combination of their Broader/High Self "desires" (from previous/future/concurrent lives), blending of desires that have been launched previously by Physical Self, and a gazillion other factors that we (or they) might not be consciously aware of yet, if ever.

All we can say for sure is that the Law of Attraction is an absolutely perfect vibrational sorting machine so the result must satisfy all parties involved. It's when that result is totally unexpected from a physical, logical standpoint that we use labels like "miracle"...but it's really just Universal Law doing what Universal Law always does.

I thought I'd add some quotes just for completeness of this answer, but mostly because I love quoting Abraham in response to Bashar questions :) ...

Everyone can win no matter which side of the political or religious debate they are standing upon, everyone. They are so busy pushing against what they don't want that what they don't want is active in their vibration. If everyone would relax they'd all get what they want and they'd have fun in the getting of it, you see.

Abraham, Mexico Cruise - 2009

...and, in regards to the election of George W Bush a few years ago, but maybe also just a little bit relevant to the election of President Trump :) ...

It's a fascinating thing to watch two different groups on two different sides of the argument. This one is giving power to that one and that one is giving power to this one. It's fascinating. The group that wins the election is the group that has been pushed against hardest by the other. We're not kidding you! Michael Moore is helping Bush win.

Abraham, Tarrytown, NY - 10/9/04

Several things at play here.

Firstly, Bashar is very explicit that your excitement guides you towards what you need, not what you want. On a spirit level, you may well need the experience of unrequited romantic love, just so you know you are still loved if this person does not love you. So the situation may be exactly as it should be, and both of you could be serving each other very well just as it is.

Then, you or your friend may well both not be following their highest excitement, which would explain the experience of unrequited love, following the unrequited excitement. In fact, both might be the case, allowing you to experience following your excitement to greater in greater degrees. After all, unrequited love can very well be more exciting than undeclared love.

Of course, there are also those versions of reality where you and that person are romantic partners. Then there are those versions of reality where you are friends, and you both found someone else. Then there are those romantic versions where one of you is kind of sort of on board, leading to very interesting dynamics. Then there are those where one of you suddenly discovers their undying love after all, only to have the other person then lose interest. And so on.

I just made all of that up, but it must be true, because it is impossible to make something up that doesn't exist in one version of reality.

You get the version that is most suited to you right now by .....w... ...r h...... .........t, to the ..s. .. .... ......y, ....... ....sti.. .. a .....c...r ...c...

(Buy a bashar video to fill in the blanks, it's the formula he repeats all the time in every single one)