The whole issue of loaning or borrowing money from a family member or friend is totally alien to me. I come from a huge family and when I was growing up there really never was a question of borrowing money because no one had any.
I have a sibling who has more money than one could possibly spend in 10 lifetimes, but when I was sick three years ago and didn't get paid for a year I borrowed from my Visa cards to make my house payment until I could sell my house. I NEVER considered asking to borrow money from him or even my dad.
When I finally got my disability pay a year later I had a friend who had been out of work for a long time and was pretty desperate. Of course she also had spent all of her severance pay (15 months worth) traveling and had not even begun to look for a job. I headed off any question of lending her money (which would have never been seen again), by just being clear that I had invested my money and it was all tied up.
I'm not saying that I would never loan anyone money - it's just highly unlikely that it would ever be more than $20.
Not that you owe anyone a reason for not lending them money but you can also just say that it's in a CD that you can't cash without a penalty or invested in stock, etc. As for the coordination of the selling and buying of a house, banks make bridge loans every day. They are very common.
And if you think I sound selfish - I gave away a huge amount of money last year but not to anyone who asked me for money.