You love him, he loves you, but there may still be a dark cloud on the horizon: his friends. If your boyfriend has a friend, who, for whatever reason, simply does not like you, it can put a serious strain on the relationship. While it may be tempting to try to win the friend over or to take the opposite tactic and write him off, your best bet is to take a neutral approach to the situation. Defend your boundaries while being respectful in order to navigate this sticky situation.
Give It Time
If a friend of your boyfriend takes a dislike to you early in your relationship, start by being patient and giving it time. It's possible that the friend has made snap judgments about you and that he will change his mind in time as he gets to know you better. Bear in mind that he may not be basing his judgments on you, but on your boyfriend's past girlfriends. This may be especially true if he has a history of dating women who the friend feels weren't good for him or who got in the way of the friendship somehow. Alternately, if he's single or unhappy in love, ask yourself if it's likely that he's jealous or feels left behind.
While your boyfriend's friend is entitled to his opinion of you, you're entitled to respectful treatment when he's around. That means keeping his negative opinions or any hurtful remarks to himself. In the same vein, if he's in the habit of repeatedly making his opinion of you known to your boyfriend, let your boyfriend know that this is not appropriate behavior and it's not respectful to him. Discussing it with him once should be enough; your boyfriend may see anything beyond that as badgering and pressuring. You have a right to ask your boyfriend to say "no" to this behavior or at very least, to avoid telling you about it.
Be The Bigger Person
Do not ask your boyfriend to choose between his friend and you, even if you believe that's what he should do. That choice is for him to make independently and he's most likely, in the long run, to choose the person who doesn't force his hand in the decision-making. If you're afraid that his friend may issue the same ultimatum, wait and see what happens. If he's willing to let his friends make decisions about who he should date, you may be better off without the relationship.
Recognize that ultimately, a friend who doesn't like you is your boyfriend's problem, not yours. As long as he is happy being with you, it's not your job to win over his friends. Instead, it's the responsibility of his friends to respect his choices and his responsibility to make sure they know that. Take responsibility for your own behavior if you believe you've behaved badly around the friend, but don't apologize for any behavior that your boyfriend usually approves of just because it offends the friend. After all, you're dating your boyfriend, not his entourage.