I recently (well 3 months) came out of the longest term relationship I've been in, it was 2 years of dating and I can understand what you mean. Everything was going perfectly then suddenly there was some huge trouble outside of our scope and relationship (problems with her family, heavy problems) which lead us to not being able to see us for a few months. At first I called her like usual, pretty much every day for a few hours but she was busy as hell with the same stuff I mentioned, she said she honestly felt horrible when she couldn't manage to answer no matter what and that I'd be doing her a huge favor by not calling as often, so it took a lot of effort but eventually I managed. Then eventually said family problems of her passed and we just didn't start seeing each other again. We eventually talked and she dumped me, I handled it fairly well but it was pretty soul crushing.
Overall try not to come off as clingy (not something I did, just something that I know is a huge down for many women) and talk out your worries with her instead of saying those to us. In the end whatever happens will happen. Hell, after breaking up with her in these months I've had more sex partners than what I've had in the rest of my life and honestly I'm not that down anymore, life moves on.
What I'm trying to say is if you can do something about it: Try. Don't let the ship sail away while you watch in silence. If it's outside of your control no matter what do not beat up yourself about it.
Overall try not to come off as clingy (not something I did, just something that I know is a huge down for many women) and talk out your worries with her instead of saying those to us. In the end whatever happens will happen. Hell, after breaking up with her in these months I've had more sex partners than what I've had in the rest of my life and honestly I'm not that down anymore, life moves on.
What I'm trying to say is if you can do something about it: Try. Don't let the ship sail away while you watch in silence. If it's outside of your control no matter what do not beat up yourself about it.