f your partner is doing something that's making you feel unloved... like not making time for you any more... or you're really worried that your partner is cheating - then it's definitely time to talk to your partner about those worries.
Tell your partner how you're feeling... and then ask your partner to be honest with you about how they're feeling about the relationship. Try and talk calmly about the worries you've been having, and see if there's anything you and your partner can do to make things better, and make you feel happier about the way the relationship is going.
It's normal for a relationship to go through changes, and sometimes people forget that you have to keep making the same effort as you did at the very beginning.
if your partner isn't actually doing anything wrong, and you think that perhaps some of the worries are all in your mind... it's important to realise that this happens a lot in long-distance relationships. It's just the distance getting in the way, and making you feel insecure. If you've talked to your partner about your worries, and your partner has reassured you that everything's okay, you just have to try and put aside all the doubts, and enjoy your relationship. There's never any way to guarantee that a relationship will last forever... but all you can do is take it one day at a time, and do your very best to make it work.