Is it normal to stay with the one you need because the one you love isn't available?

Done that, didn't end up great, I ended up realising I couldn't keep it up anymore, I also realised I hurt person Y, and X was still unavailable, and being with someone to forget X was stupid, I had to forget X on my own first.

If X is unavailable, then X should not even be a factor to consider here. The real question is about Y. Don't compare Y to X, consider Y on his/her own--- what is it about Y that makes you hesitate, other than that he/she is not X? Not knowing all the details, my instinct says stay with Y, things don't sound bad and you have kids. But I don't know all tbe details.

Just to make things even more complicated, X is a friend of a relative of Y and lives in a different country. Hence leaving Y would certainly mean never seeing X again.

Settling is the worse thing you can do.

1. You don't love who you're with. If one day X were to go, "I would date you, but you have someone already," you would probably dump Y in a heartbeat. That's fucked up, and shows how pointless the relationship was from the start, so why bother? Loneliness? He/She is "good" to you? She/he is what you "need"? All pathetic excuses to use someone to fill your own void, when you can solve these feelings on your own if you tried.

2. You wont cherish him/her as much as they deserve. Your dissatisfaction will show, especially if you're still keeping in contact with X, and watching their progress in life; including their relationships. For example, if X were to get a new haircut and look super cute with it, you may (without realizing it) suggest to the warm-body (the person you're "dating") to get the same haircut. You'll probably do a lot of things that will indicate that the person you're dating just isn't good enough compared to the person you're obsess with, and believe me, that person will noticed more than you think he/she would.

3. It's a waste of time for you and for the person you're dating. Unless you're an expert actor, and can act for years, the relationship will eventually come to an end. Either you're going to get tired of pretending to love this person and being in a loveless relationship, or she/he will; and that could take months or years depending on how oblivious or in denial your partner is about the situation, or how much you want to hold on to this pointless relationship.

It's best to stay single, and sort though your feelings for X; even call X for closure (confess or whatever). If dating X still impossible, then you need to work on getting over him/her, and accepting that it's not going to happen. There are billions of people in the world, and we're all compatible with at least a couple thousand in any given city, she may feel like "the one," but realistically, you have many opportunities to fall in love again if you allow yourself. So go through the motions. It could take months, or years depending on whether or not you're ready to let go of this obsession.

I hate math, but since you asked

if
(x + y)2 = x2 + 2xy + y2

then you should probably just give up.

-Pantz

Nobody "needs" anyone. If you feel like you need someone that is a sign you need to work on yourself.

It seems X is out of the question.
Keep them as a friend but move on.
If Y isn't satisfing maybe you need to move on and look for Z.

True, but kids are involved, and that's another form of love that trumps romantic love by a long way. And X certainly isn't 'some nice piece of ass', for which I wouldn't dream of leaving Y in a million years. X has merely shown me that what I thought to be romantic love (because I had never felt something so strong before) was merely an insipid version of it. When X came into the picture it was like a chemical reaction that didn't need to be catalysed.

Why does it say 10 comments and yet I can only see 5 (now 6, with this one)?

It's a possibility I'm alert to, but the point is that X is the one I want. That may change in 10 years, if I ever meet somebody I can love in the same way, but it doesn't alter the question of whether it would be sensible to settle for Y or perhaps go it alone.

Yeah I guess I've already settled rather than stayed alone at times.

x=y^2

Didn't Stephan Stills write a song about this back in the seventies?