Here's a few ways anxiety can play a nasty role in your dating life counted down from least frequent in my opinion to most. Anxiety can have a particularly frustrating and even depressing effect since no matter how you develop emotionally or physically--very little will matter if you are always subject to your own anxiety.
Makes you: Angry
Anxiety can make you a grump grandpa for no reason at all. Your general worry and fear of things turning out bad or dread of things in your future you don't want to do or guilt and shame of things that happened in the past will make dating a difficult ordeal. If you're single and trying to meet someone, your whole vibe will be a little off. If you're getting to know someone by going on some dates you may come off as bitter and resentful even though you're actually not that unhappy and have a pretty good life. And if you're in a relationship every fight you have will be intensified and even when things are good your anxious mind might be searching for things that are bad with the relationship that aren't big deals until you nitpick at them until they are. This is all because your anxiety is a part of you sure, but it is not real and it has no it has no basis in reality. It is often a projectin of your ego and of an inability to be present in the moment. There is nothing wrong at the moment but your anxiety tells you there will be. Even the most attractive person with the most attractive personality who has the anxiety monster in them will be very ugly.
Prone to cheating
A lot of people who actually go through with cheating, I've found, actually do so in response to anxiety. For girls, it tends to be when they're having problems with a boyfirend and another guy appears as the solution. Often after cheating, they will feel guilty and try to stay in the current relationship or they won't feel guilty and will still try to stay in the current relationship. Obviously, once they've cheated they likely no longer feel the same attraction they onc ehad but since they're the type to cheat instead of break up in the first place they usually want/need that safety of being with someone. Another corelation between cheating and anxiety...many have an unreasonable fear of getting cheated on which manifests in them actually doing a lot of the cheating--the tell of a person like this has become well known: if you're constantly being accused by your partner of cheating or wanting to cheat and have done nothing to suggest that then they are the ones who are probably cheating.
Prone to breaking up
Somewhat similar to cheating. A big part of the anxious person wants to break up if only to stop their anxiety from chocking them constantly as a result of being in an intimate relationship they're clearly not mentally ready for. For some, the break up sticks and they simply move on constantly. For others, it's a breakup that only last a few days and becomes so tiresome that the partner just moves on eventually with their own break up that sticks.
Makes you: believe in conspiracy theories
I have a theory a lot of crime/thriller novelists are extemely anxious/paranoid people. While it's great for creative writing, it's terrible for relationships if it spills over. Your anxious mind can produce any kind of fantastic story. She's not really going on a trip to Disney world with her brothers, she's really going to Miami with them so she can meet up with her friends there in secret and go to a party to let loose because you're too stifling and she wants sex from other men and her brothers lowkey know this and are covering--oh wait she just texted me a picture of her with a goofy hat at magic kingdom and her brothers are only ten...man, gotta' start meeting people's families....
Makes you: boring
Dun, dun, dun. While obviously no where near as dramatic as the others, I'd say that being boring is a pain that just keeps punishing. It's a leather whip that one gets just for being "nice." Anxiety is the reason a lot of "nice guys" are this way. They can't think of anything to say and so they just say something nice. Think about it this way--they laugh and horse around with their friends with a lot of confidence in the way they act and the things they say...they know what a cool guy is like at least according to them. Yet, anxiety makes it so none of their actual personality comes across at all. So many awkward silences, so many poorly delivered jokes, so many offensive text messages meant as compliments. Anxiety is the thing that causes many a nice guy to go rogue and start being a woman hater instead of just maybe for once trying to calm down and be cool and have a personality. For girls as well, i've seen many a girl clamp up and just agree with everything i said and sit there mostly speaking in one two sentences at a time. Of course, there is a thing as too much personality but anxious has a way of stripping you of one entirely.