HiCustomer Thank you for asking your question on JustAnswer. By the way, it would help us to know:
-What are your ages?
-Are they picture of girls online or girls he actually knows?
-Is this a committed relationdship?
-Could you explain your situation a little more?Thank you again for trusting us with your problem. Please reply as soon as possible so that we can finish answering your question.
You need to tell your boyfriend your concerns especially about the lack of sex lately, ask him if you are not enough anymore. Tell him you feel as though things have changed and not for the better. You may want to tell him that you got into his email and ask him about all of the girls but if you feel that will create another riff between the two of you then don't tell him but if you do not tell him about it that will make you no better than his lies. Trust and communication and sex are a necessity in a relationship and it doesn't seem like you have any of those right now and something has to change or else the relationship is in major jeopardy and won't last much longer. Tell him you want to trust him but with everything you've found out he is making it very hard to do that. There has to be something going on that your sex life has dwindled a bit it could be because he may be finding other means online, like porn or cyber and you won't really know that unless he is honest with you about that.
If you can not get him to tell you anything and be honest with you that may mean you need to give him an ultimatum and stick by that ultimatum so that he knows you're serious and mean what you say, he has to know that you are fed up with the way things have been between the two of an d can't take much more.
If he expects you to respect him and not talk to other men then he has to have respect for you also and stop talking to other females he can not be a hypocrite and tell you what to do and then tell you that you are being possessive when you give him the same treatment. If you do not have concrete proof that he is doing anything else other than just talking to these female the only choice you have until he gives you reason to doubt him is being just friends with these girls you have to trust him and show him that you trust him. If you didn't read anything inappropriate then you have to believe that he is being honorable. If he will not change his ways as far as all the other females are concerned then you may have to rethink if you want to be in a relationship with him it's not fair for him to tell you stop talking to someone you have known for so long and is like a brother to you but I think he may have issue with the fact that he is not related to you and he is of the opposite sex, either way with all of the females he talks to he should not have a problem with someone that is like family to you.
Tell him he says he loves you then he has to start showing you through his actions and having respect that he is with you and not talk to so many females when he has you. Tell him you need to feel wanted and needed by him and that sex is important part of that need.