Have you ever started a relationship with someone whom you knew ahead of time was moving away in a few weeks or months,

Yes. And, I was happy to see him leave. He was only a catalyst. 

My first ever apartment I had a male roommate and we divided it by hanging sheets and bedspreads except we both used the kitchen and bathroom.  And we went our separate ways and lived our separate lives for months until shortly before he was moving out. His name was on the lease so I knew I would have to leave as well when he did and I already had a boyfriend I would be moving in with but he lived at some remove so we could only be together mostly on weekends when he didn't have to work.  I guess I was sort of interested in my roommate and I of course had heard him with girls he brought home but never thought we would get together or anything like that. One evening out of the blue a few weeks before moving out he came over to my side and things just happened which I guess I had wanted though I was not admitting it but those few weeks were just great and he was concentrating on me and we talked about how we wanted out lives to go and what we wanted to do with them.  I was sorry when we had to break up because I liked him quite a lot and had come to know him well but I had a regular boyfriend I was moving in with so that became my focus. This post was edited by officegirl at February 20, 2019 6:02 AM MST

It's never happened.

But if I'd found him highly attractive and I'd been single I would have turned him down.

Casual has never attracted me.

When I was a kid my neighbor across the street had a grandson who lived out of state.  He was a year older than I.  He would come in the summer to work at the steel mill that we lived next to when he got old enough. Prior to that he would come and stay about a month.  Every summer we would have great fun.  He continued to come to work in the summers all the way through high school.  He was going to college on a basketball scholarship the next fall and wouldn't be coming to spend the summers any more.  I was already involved with who would become my husband.  A part of me wanted to just leave and go with the guy I had looked forward to seeing every year since around the age of 13.  I didn't, even though he wanted me to.  The night before he was leaving the last summer he was there he came over and knocked on my window around 1AM.  He did that sometimes.  I could climb out and we would sit on the front porch.  I remember not wanting to say goodbye to him but had to trust my decision.  By the next day he was gone and my boyfriend was at my house I felt like things were as they should be.  But I've never forgotten that guy.  He went on to the NBA for just two years then coached at the college level for a few.  He is an architect.  I haven't talked to him in a long long time. This post was edited by Thriftymaid at February 20, 2019 5:22 PM MST