There can be many reasons. Being tired, stress, both in general and having to perform. Age. The biggest part of sex is in your brain, so you may not be turned on by your partner as much as you think you are. If you feel you climax without ejaculation there can be a Plumbing problem. Physical blockage. Bottom line is go to a doctor and find out.
this could be because you man is not excited by you or because you aren't lubricated good, or it could be that he has GREAT stamina. Could be a number of things.
becoming sexually aroused, and a rush of blood to the penis.
It causes a donkey to become sexually aroused.
Yes. The prostate is stimulated which causes ejaculation.
You're not aroused, or sensation dulled by another substance
Yes, pre-ejaculate can result in pregnancy. Pre-ejaculate itself doesn't contain sperm, but if the man ejaculates and doesn't urinate sperm can remain in the urethra and thus be carried along by the pre-ejaculate. Although the number of sperm that could be in pre-ejaculate are only small compared to how many are in ejaculate, there is still a risk of pregnancy.
because of the constiction on blood vessels around the nipplles
the most causes of someone becoming refugee is, war,persecution,natural disaster,famine and etc.
Lack of the hormone estrogen, nervousness or insufficient time / stimulation to become fully aroused.
Everything
It is a natural state in where the body (being the man) gets aroused by something or someone, this causes, without much control releases a hormone which gives you an Erection... but it depends on the fact of if you are talking about in the morning or just whenever.
Check google everything is right on there
OCD