Yes, it is possible.

Are you defining "sex" and making out and foreplay, or, as intercourse?

The reason I say that this is possible is because each one of us, male and female, quickly develops a routine of motions, rhythms, and pressures, soon after learning to masturbate that we then rely upon for the rest of our life to bring us to the brink of a climax and then beyond. Oh sure, it is possible to vary the method of how we stroke a penis: http://jackinworld.com/sitemap.html
(see the "How-to" and "Expert" pages)

yet if we do not also include our specific technique then an orgasm will either not happen or will be less than desired.

Very often a guy can be stimulated orally and achieve a state of bliss, sexual tension, and excitement much more intense than what is required to trigger an orgasm, yet it won't happen. Why? Because the pattern of stimulation is incorrect and not what we have come to rely upon to trigger an orgasm. Think of this as a "Y"-shaped fork in the road in which we begin making out at the bottom of the Y and work our way up. If our approach is to take the left fork then we will eventually reach the peak of our arousal followed by an orgasm. If we follow the other fork, in which we are stimulated orally, we will attain a much more intense level of arousal, excitement, tension, and anticipation, that extends beyond what we experience when working on an orgasm, normally. These factors continue to build and build because as fantastic as the sensations are they are not what we rely upon to trigger an orgasm so it just won't happen. The fix is to pause at some point and let the intensity and sense of urgency subside and then to switch forks and go after the orgasm using the tried and true technique that he has developed.

> After my bf masturbated, and we had sex again he was able to cum, is that normal?

(Did you mean "unable"?) How long did you wait before trying a second time? Please keep in mind that the down time or "refactory" period is different for men and women. The female of the species can enjoy multiple orgasms in rapid succession; whereas, the typical male has to wait perhaps as long as thirty minutes before his system is ready to go, again. Now, having said this, and, depending upon a person's age and how he is "wired", the down time can be anywhere from about five minutes to as long as twenty-thirty minutes.

Subsequent orgasms in a multiple string can sometimes be more difficult to trigger. It is not unusual, therefore, for a couple (or a guy if alone) to have to work harder to trigger the second or third.

There are things you can do to help jumpstart an illusive orgasm.
* Fingering the Anus and Sphincter muscles
* Massaging the Prostate
* Squeezing a testicle

All of these forms of stimulation work in conjunction with whatever else you may be doing and will greatly enhance and intensify those feelings.

The Prostate can be felt as a small walnut-shaped bulge in the front lining about 2" inside.

Under normal conditions, squeezing a testicle just enough to cause a mild ache is not painful, just annoying. Doing this same thing when a guy is extremely aroused is interpreted by the brain as actually quite enjoyable. (There is a fine line between pain and pleasure.) If you want to try this, then practice when he is not aroused in order to learn just how much pressure to apply to cause the mild and annoying little ache. Then, when he is really aroused and at the trigger point of his orgasm, you can do this along with other caresses (including intercourse) and it will intensify those as well as to help trigger the problematical orgasm.

The same goes for massaging the Prostate, although, there is no pain involved, just pure unadulterated pleasure from the beginning.

If you do not want to do either of these, then finger the outside of his anus with a lubricated finger. If you want to be more bold, yet not so bold as to involve rub his Prostate, then press your finger inside just to the first knuckle and massage along the sphincters with a stroking and undulating finger motions.

Have fun!