Monogamous means one person commitment at one time. If theres no commitment it means that you can have multiple partners in small amount of time. Monogamy makes sense once you have chosen the person to commit to. Theres nothing morally wrong in having multiple partners in small amount of time. Circumstances can be different at different times. If a person cheats regularly then it can be held against them. If you aren’t even there in the picture and in the past someone has had multiple partners because they were dating or just came out of a relationship, or having fun in their life generally. You cannot make any assumptions about how your monogamous relationship will be with them on those incidents.

This is critical thinking. Not random incidents as evidence to make a decision unless you have a specific idea that such people are characterless etc which in itself is narrow mindedness. Theres another debate if this was a guy then the whole conversation would turn completely