The bedroom is the one place where you will find out how sexually great a woman is, or is not. It's a type of litmus test where all the potential hangups and insecurities are aired like dirty laundry. If a woman is confident and enjoys sex there will be no games and sex will happen quickly. But if she has doubts and was perhaps burned in the past she will resist having sex and won't want to repeat the "mistake".

Many psychological issues women have are centered around sex, so it makes sense that the bedroom will be the one place where they tend to come out all at once. Your patience should be limited in this regard. Pretty much the only time it's probably okay to invest extra time and effort is if a woman is young and inexperienced (e.g. a virgin). But all other times it's either shit or get off the pot.

If she just can't seem to go through with it then there's no reason for you to hang in there, hoping the situation will improve. It almost always does not. Remember, no orgasm is worth a lot of your time and effort, especially for a man where it lasts less than a minute. Much easier to go to the bathroom, jerk off for a minute, and be done for the day. Move on. Tell her you have things to do. In some cases you should burn your bridges right then and there if the situation is too fucked up.

Other times it's okay to wait another time (maybe she is having her period). But let her reach out to you for the next get together. This way you know she genuinely wants to have date with you.