For guys, too much masturbation can make it more difficult to get hard and to reach orgasm. This tends to be more of a problem as you get older - guys can generally only reach orgasm a few times a day, and as you get older that number tends to come down.
Also if you get too used to the feel of your own hand, and how you bring yourself to orgasm, then it's possible you might find that it's harder to reach orgasm through sex, since the sensation is different, and you don't have complete control of speed/intensity (depending on position).
I never had a problem having sex, and masturbating as frequently as I felt like it, until around my mid-30s - then I went through a patch of finding it harder to stay hard, and to reach orgasm. Cutting down on the masturbation certainly helped with that, along with other stuff.
There is no universal pattern how masturbation can influence the reactions during sexual intercourse. One of the reasons is that there are so many different kinds of self-stimulation and different people are prone to different kinds of "wiring" their brains to external or internal stimuli.
In general I would say that the older you are, the less probable it is that your masturbation will affect your reactions during intercourse if you have already had a history of sexual intercourses in your past.
Second, it depends on the forms of masturbation and conditioning your brain, I mean, for example masturbation can under ceratin circumstances contribute to quick ejaculation and under different circumstances it can lead to delayed ejaculation and prolonged intercourse - e.g. if you masturbate too quicky and as soon as you get aroused you masturbate frantically and you are done after a minute, if you repeat this pattern, then you can be prone to similar reactions during intercourse. The opposite effect can be if you get used to your hand and then you will find it difficult to reach orgasm in other ways during the intercourse. Or if you train your body to last longer during masturbation - e.g. you watch porn for 2 hours without touching yourself or you masturbate for a while and then stop doing it for a while and let yourself orgasm just after a long session, then it can prolong your performance also during partner sex. Or if someone masturbates ONLY with using porn, then he can find it difficult to react to sexual stimuli of his partner without the visual help of porn or fantasies of similar stimuli in his mind.
So there is no straightforward answer and it can have quite opposite results.
I think that if you masturbate when you feel a strong physical urge to masturbate after a period of sexual abstinence, it will not change anything in your sexual life with your partner.
All in all, I would recommend to change the forms of stimulation and to implement different patterns of self-pleasuring (with and without porn, fast and slow, quick and delayed and slow, using just your hands and using different material objects for stimulation, different fantasies, different kinds of porn - not just one special kind etc...), then your sexuality will become more flexible and less rigid and you will not experience any dramatic changes in the patterns of your sexual reactions with your partner.
it affects it in a good way because if u can make urself into an orgasm by urself it makes it betterwhen som1 does it for u