I would suggest a therapy group for social anxiety, if you can afford one (they are not very expensive), or, failing that, a free peer support group for same concern.

Another idea, if you play any kind of sports, is to get into a regularly meeting group to play - racquetball, whatever, something. He has his tennis and you have your racquetball. See how that would feel for you (you need to try - picturing how it might feel would not work; it has to be happening in reality).

Another idea is to call your public library or your public school district and ask if they need volunteers to teach literacy. I do not know where in the US you are; in any state with a significant influx of Spanish-speaking immigrants you would find a need for English literacy teaching. You will feel so much better - somebody would need you and you would give that somebody the MOST important skill for survival in your country.

Currently you might be keeping the bf on a tight leash because you have nothing better to do. Also, you seem to overconclude. It might be that the bf is a people pleaser - you know him better - but from that one incident in which he kept an appointment for a tennis match instead of talking over the issues in your relationship, he was simply appropriately polite and appropriately committed to being punctual; he was not a people pleaser - your conclusion went too far. I think that because you do not have much to do, you get that distorted impression that everything revolved around you, in a negative way, but still around you. That the bf kept his match appointment is not about you; if anything, it portrays him as trustworthy because keeping appointments and not being late are one facet of trustworthiness.

So I hope you can focus on yourself, your life, your interests, and your capacity to be of service to others and derive pleasure from being of such service (the literacy teaching example would go here). You might then surprise yourself by how you little you'd care about your bf's friends. And you will be in a better position to evaluate this relationship/