It is so important for you to do things that you want without anyone stopping you. If you want to go on that trip for spring break with your friends, go, or you want to go out and spend time with your family, do it!
Never let anyone stop you from doing the things that make you happy! If it's joining a club, sorority, going on a trip, no matter what it is. Especially your significant other, there is no reason that your partner should tell you no you can't do that, or that's stupid why would you waste your time with that. That isn't fair to you, because they should be supportive and be your cheerleader. Not acting as if they own you and control what you do, they shouldn't act as your parent because you are both equals.
Now to a certain extent, if you are joining something that isn't good, or won't is a positive experience, etc, if your significant together explains why they believe you shouldn't do it, then there is a difference between them flat out saying no you can't do that.
Relationships are all about balance, if you are just filling your schedule with a million things, then your significant other feelings a certain way is only normal. There has to be a balance of things outside your relationship and time you spend doing things that don't involve one another but you still have to make time for each other.
But if they are just trying to be controlling then tell them bye because you need to be able to live your life and do what you want as long as it isn't counterproductive and harmful to you. Never let anyone get in your way of bettering yourself or making yourself happy.