We are bound to repeat history over and over again when we fall into a fearful state of mind. It is comfortable to fall back into familiar patterns when we feel that way--even if they aren't ultimately the best for us, because that's what we know. Change is incredibly difficult when we do not feel comfortable making the leap into unfamiliar territory, particularly in romantic relationships.
Choosing a partner can be fraught with fear and discomfort if you are looking for someone different or a type of relationship which you haven't pursued up to this point. For example, you could have be fine with hook-ups or FWBs in the past, but are now considering a more serious, committed relationship. The issue here is that there are core differences to the general feel of who you're with and how the relationship progresses that makes it uncomfortable for a time. Priorities have shifted, wants and needs have shifted, levels of emotional and physical connection have shifted.
Once you are able to register this shift, you may have new feelings stirred up within. This is completely okay and expected, however. What is most important is that you've considered what you want in a partner, what your deal breakers are, what you are willing to compromise on, and are able to express that fully and honestly to relationship prospects. I am a full believer in directly asking for what you want, but also sticking with what I am and am not able to compromise on. Know that all of this is based on your present self--you are not a fortune teller and, therefore, cannot speak for your future self.
Do not make decisions about a choosing a partner based on how you may or may not feel about them at a certain point in time--you cannot make accurate judgments about your or their future feelings whatsoever. Unless there are certain huge life factors that you absolutely know will come into play in a more serious relationship (e.g. differences in wanting kids or marriage), all you are certain about is what you want right now. Or what you would like to remain an option in the future (e.g. the potential for a long-term relationship, more physical intimacy).
Do trust your gut to lead you in the right direction. Feeling a strong connection with someone does not happen very often, so if you are serious about a person, do not allow the details to push you away from a potentially beautiful relationship. Be able to compromise and work out issues in tandem if you have the courage to keep moving forward. Committing to someone can be terrifying if you don't know the future--it opens you up to the possibility of great pain, but also closeness, connection, and pleasure. Take a leap of courage, don't back away in fear of what lies ahead.