I think it's a little too soon to panic. A month and a half isn't very long, and it can take a while to learn what a new partner wants in bed and get in sync with each other. Some people are also slow starters sexually, and tend to hold back a little until they're fully comfortable with the relationship.
You are not wrong to be concerned; it's definitely a red flag. He could very well turn out to be a lousy lover. But if he's great in every other way but sex, you should give him some time to get better. Maybe you have a lot more experience than he does. You also don't say how much sex you've had in that month and a half. If you've only gotten horizontal 4-5 times--and I'm not asking, so don't tell me, I don't wanna know--then you've barely started.
You say you "keep trying" -- how so? Are you communicating with him in bed, telling him what you like and don't like? That's obviously step one. Everybody's different in the sack, and there's absolutely nothing wrong with instructing a new partner on what you want and how you want it. Most guys want to please, so he should welcome some pointers. (If he doesn't, that's a huge red flag--even bigger than the underwhelming sex. You have to be able to communicate without your partner getting his/her feelings hurt and shutting down.)
Great lovers aren't born, they're made. And they're made by learning a little more from each lover. It's called experience. I say give this guy a bit more time and a bit more instruction, and see what happens. If nothing changes after a few weeks, then yeah, you have a problem. Right now, I think it's too soon to call.
Dating only a month and a half and already she's worrying about sexual incompatibility? Seriously? That seems WAY too early to be thinking about that to me. After a year and a half, that might be something to be concerned about, but at this point, she ought to be worrying more about getting to know him and finding out his values and personality and likes and dislikes. Call me old-fashioned (or perhaps just old), but I think it takes much more time than that to really get to know a guy and find out if you are compatible with him, not just sexually, but in other ways as well.
Great answer, and the first tag made me chuckle, by the way. :-)
Im sorry i have to disagree. Sex is a huge part of a relationship and often incompatibilites in certain areas manifest themselves in the bedroom. Sexual chemistry is definitely something important enough to evaluate within the first couple of months, definitely within the first 6 months of when the couple starts having it. I know that in those early days personality aspects and values are really important to be getting to know, but I think sex communicates a LOT and to ignore a red flag like that is just asking for trouble later on.
I've got the same problem, but the problem is even worse - sex is not even happening because I keep tightening up (I think I 'hold back until I'm fully comfortable with the relationship' like Cary said because this also happened with my previous partner and it took a while for sex to happen). Things are great between us except for this, but I think he's frustrated with trying (although we haven't even tried many times, and I told him I had the same problem with my ex) and now he thinks we're sexually incompatible and wants to end things. How do I convince him to keep trying? Or, since he wants out so soon, is he even worth pursuing?
If you want to be happy in a long term relationship, then sexual compatability is very important in my opinion. I agree with Cary that you need to clearly communicate what you like, need, do or do not want. Just because you have had better sex does not mean that this guy is wrong for you. But do not expect to be happy in a relationship is the sex is bad or you 2 just are not compatible because sex is an important part of long term compatibility I think. He may not be very experienced but he should be willing to try in any way that he can to satisfy you. If he cannot do this or is totally inept, then it may be best to move on. Good luck.