hey man not as easy as you think. i've been in that situation. when i was dating my japanese girlfriend. that girl just wanted it all the time like you would not believe. we would have just finished and i mean just finished and she would want more.
she would get pissed off if i couldn't get going again after just cumming in less then 10 minutes. we would go three times a night or sometimes more. i couldn't believe what was happening but i began to not really like it too much.
at first it was great but it really wares on you after a while. especially everyday after a long day at work. also remember this is the same girl that you fuck two to five times a day every day. it tends to get pretty stale and hard to do. you find yourself having to watch porno or something just to get hard or have her suck your dick forever to get hard and hear complain about its taking too long.