what happens if i were to die prematurely and by then still did not have sex or just started to have sex?

in both cases, it would be bad because you have not enjoy sex before or you have only enjoyed it a few times.
given that you are alive now, you should not be afraid that one day this situation will happen and tell yourself you must not let this happen. this situation can happen to me and if really does so be it. accept the reality if it is going to happen and be calm about it. when you are feeling okay now, be calm. if it really happens, you should also be calm.