Every relationship involves a certain amount of compromise, but you should never give up fundamental parts of who you are just to be with someone. You may have specific activities you engage in which s/he isn't interested in or a commitment to your career which may require you to work on short notice. You might have children or other family members who need tending to, and you most likely have expectations about what you require in a relationship and what you are willing to give. Obvious boundaries such as not cheating or not engaging in physical or emotional abuse may go without saying, but it helps to know and acknowledge them before they come up in a relationship. The more you know about yourself, the easier you can convey your needs to your partner.