If you mean in a relationship, I believe forever is something you can't plan on, but it's something you can work towards and sometimes you'll succeed, but you won't know if you've succeeded at until you get to the end of your life. I know for me, it's not something I could ever promise or guarantee.
Yes, I believe in forever. With a twist. There are some things in life you just can't avoid but when it comes to forever, I think it's really subjective. This probably won't make any sense to anyone else, but I think forever is as long as the relationship is viable. Eh, it's late...I'm rambling.
A lifetime together is definitely possible. People do it all the time. Like others have said though, it doesn't just happen.
A HAPPY lifetime together takes work, cooperation, compromise, commitment, communication, etc. I don't want just a lifetime together, I want a happy, fulfilling lifetime together. As long as both of us remain dedicated and willing to work towards that, we'll achieve it.
Well I'll consider that you mean in long term relationships so I'll say that yes I do. I believe in reincarnation and I believe my lovers and I have been together in many lifetimes both past and to come. I do believe that sometimes you work out what you needed to and move on but I don't believe you ever stop loving someone.
Like has been mentioned before; keeping love alive and in good repair takes commitment to hard work, and a serious drive to work out whatever problems come along.