Do you recognize yourself in all or any of this?
Because of various reasons, you have not been able to train nearly as often as you planned
You feel guilty for missing out
You are thinking about quitting
You have missed so many training sessions that there seems to be no point in continuing
A lot of people think like that. This is normal. However, this "all or nothing" mentality, for one, is not healthy. Secondly, it is not correct that it is better not to exercise at all than to exercise little. It is the other way around: It is so much better to exercise little than not exercising at all. In fact, this is twice as good!
If you worry that your training mates have become better than you in your absence, then this may also be unfounded. Your training mates have probably also been a bit away from training. Virtually no one attends all the training sessions. Besides, don't worry too much about what other people do. Everyone trains on their own terms. Concentrate on your own training. You'll be much happier. Probably a better performer as well.
So don't give up training just because you haven't been able to train as much as you planned. There's no reason for that.