You meet a man/woman and hit it off immediately, just click on all levels and it's incredible. Then your beloved informs you that he/she is terminally ill and likely won't last another (let's say) 2 years.
Would you walk away, knowing that the relationship has an expiration date, or would you enjoy it for as long as it lasts? Would the joy of the love and commitment you have outweigh knowing for certain that you will not grow old with this person?
You know... in so many ways - probably in most ways - life really is pretty simple, we humans just like to complicate the hell out of it for whatever reasons. Boredom maybe? Who knows?
But anyway... I'd say the answer to your question depends, but in real life it's a self-answering question. One of only a few possibilities reveals itself. When you don't spend time with that person, you miss spending time with them - you long to spend more time with them even though you know they are going to die fairly soon. Or, when you don't spend time with them you don't miss them and don't long to spend more time with them. Either way you have your answer, the Universe is telling you what to do. Similarly, when you do spend time with them, you feel great and happy and contented and feel that's where you belong. Or, when you do spend time with them, you don't feel good or happy or contented or that's where you belong - or you feel uneasy for some reason, perhaps because you're always aware that it's going to end soon enough. Either way you have your answer, the Universe is telling you what to do.
The Universe usually tells us what's right, tell's us what we should do. Too often we do our darndest not to hear it or trust it, and that's usually when life gets needlessly complicated (and, more importantly, we end up less happy than we could be).