Why would she dump you if you don't finish, or finish more slowly, as long as you give her a good time? Going a long time is better than a lot of boyfriends, who go too quickly and their girlfriend doesn't have time to have an orgasm herself. *Does* she have an orgasm every time? If so, you are doing well for her.
My suggestion is to talk it over, not to hold it in and get anxious (which throws cold water over a good time in bed anyway). Tell her that your focus is on her pleasure, and that if you seem to be going too long to the point where she's had all the orgasms she wants, she should tell you, and you can stop. If you take the nervousness out of it by talking about it, things might relax a bit and both of you can have a good time.
This is a problem most men would kill for, or at least younger men. Seriously, the longer you can go, the longer you can enjoy it and the longer she can enjoy it. But the important thing about sex is, most people don't look at it like they look at other things they do. For example, if you play a sport, I'm guessing you're getting better and learning more about it than when you started. Same with sex. The more you do it, and often the more partners you have, though we all wanted that first love to last forever, it just didn't, the more you learn about different ways to do it. There are reasons some men take a long time to reach orgasm. Often it's caused by medication. If you have sex several times in a short period of time, it will take longer to orgasm as you go along (and they will probably get weaker as well). If you do last an unusually long time, you can finish in other ways than intercourse. It's all good as long as you and your partner care for each other and communicate. Which is where the problem usually is, that it's very rare that any couple actually enjoy doing it the same way. What one enjoys the other may not, and vice versa. As for women reaching orgasm, when you're lucky you'll know it when they do. Most of the time, though, you won't, and much of the time they don't. If they don't tell you this you won't know, because not everyone is demonstrative when they do reach orgasm. With a man, you always know, because of the ejaculation. With a woman, you will only know for sure if you get to know her well. Some women fake it to get it over with. Life is not ever completely equal when it comes to people, and men and women are not the same. I wouldn't overthink this stuff, therefore, but just enjoy yourself, do the best you can to make sure she does too, but also recognize it's her responsibility to make it happen for her since you will most often not really know. When you're lucky, though, do know that unlike you, women can reach orgasm many times to your one, if they choose to do that and like to do that, but your one will probably be a lot more powerful actually if you do delay it. The above asks, does she have an orgasm every time, and that's why I'm saying, with most women you really won't know. Now, when you are in a serious relationship and your older and more experienced, it's much easier to talk it over and also you get to know the person better and yet even then, I've been in relationships for years where I can't tell you if the woman had an orgasm or not and been in ones where she has one so loud and powerful every few seconds you wonder at the miracle of it all. Don't expect it to always be what someone else tells you it should be, life is always full of surprises. The kicker is, sex is really a lot of fun but it's never the glue to a serious relationship. When it is the glue, it's okay to enjoy that but don't mistake the joy of orgasm with the joy of intimacy and love. Peace.
How delayed are we talking about? Are you giving yourself enough time?
It's always good to talk to your doctor about it to rule out any kind of physical reason that might be causing this. Once that's ruled out, you can figure out why it's happening with your girlfriend.
Are you really worried about pleasing her? Do you feel anxious?
Are you going right into sex, or are you doing any kind of foreplay?
There are a lot of factors to consider, and it's something you can work out with your doctor. This article may help - https://www.mayoclinic.org/diseases-conditions/delayed-ejaculation/symptoms-causes/syc-20371358
Thanks for the responses. I would say over 30 mins.. I just feel bad that I can’t finish or it takes a whole lot of effort on her end after she’s already finished/tired. For instance, we can go a couple rounds and she’s loving it, but then I can’t finish. I get anxious as soon as I notice it’s taking long. I have only been able to cum twice from oral after we’ve been going for a while. It feels better every time, not sure if it will just get better over time or if it’s worth talking to a dr.